Guide: Identifying Headlamp Bulb Base Cap Fittings

What headlamp bulb type do I need?

A handy photo guide to identifying your headlamp bulb base fitting, with links to more detailed descriptions and the product options available for each type. With so many different headlight bulbs and sockets fitted by automotive manufacturers over the years, it can be difficult to identify the correct bulb to order. So, with your existing bulb in hand, here is a photo chart to help you select a replacement or an upgraded bulb to fit your bulb holder.

	APF P15D 30 American Pre-Focus bulbs with a 15mm diameter double contact cap, fitted with a 30mm diameter plate with three small holes and three larger distinctive comet-shaped holes, and twin filaments. See Bulb Type APF P15D 30 with links to related product options. LED bulb options fitted with this base are also available here
	ASY UEC P45T Asymmetric bulbs for older ‘Duplo’ style headlamps fitted with the European code, P45t, round turreted base with three spade connections and distinctive 41mm diameter round glass globe. Twin filaments. See Bulb Type ASY UEC P45t with links to all related product options. Halogen bulb options fitted with the P45t base are linked here. LED bulb options fitted with the P45t base are available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	BA21S and BA21D ‘Marchal’ type bulbs with a 21mm diameter single (BA21S) or double (BA21D) contact cap fitted with three equally spaced locating/bayonet pins. Distinctive 40mm diameter round glass globe. Single or twin filament options and clear or yellow glass are available. See Bulb Types BA21S and BA21D, both with links to related product options. LED bulb options fitted with the BA21D base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	BOSCH BA20S and BA20D Bosch-type bulbs with a 20mm diameter single (BA20S) or double (BA20D) contact cap fitted with two opposed, flat locating tabs. Distinctive pear-shaped glass. Single or twin filament options are available as well as clear or yellow glass. See Bulb Types BOSCH BA20S and Bosch BA20D , both with links to related product options. LED bulb options fitted with the BA20D base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	BPF SC P36S, BPF DC P36D and P36D Halogen – British Pre-Focus (BPF) type bulbs with Single Contact (SC) P36S or Double Contact (DC) P36D bases 22mm in diameter (so sometimes referred to as P22S or D) fitted with a 36mm diameter plate with one half-round locating notch. Distinctive tubular-shaped glass. Single or twin filament options are available as well as clear or yellow glass. See Bulb Types BPF P36S LARGE, BPF P36S SMALL, BPF P36S HALOGEN, BPF P36D SINGLE FILAMENT, BPF P36D TWIN FILAMENT and BPF P36D SHIELD, all with links to related product options. LED bulb options fitted with the BPF SC P36S and BPF DC P36D bases are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	SCC BA15S Originally called the Single Centre Contact (SCC) type base, now BA15S (or 1156) this is a 15mm diameter cap with two equal/opposed bayonet pins on the cap and a single axial or transverse filament. Used in many bulb applications, but for head and spot lamp application, usually with a 38mm diameter clear glass globe. See Bulb Types BA15S SINGLE TRANSVERSE FILAMENT, BA15S SINGLE AXIAL FILAMENT and BA15S HALOGEN T10, all with links to related product options. LED bulb options fitted with the SCC/BA15S/1156 base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	SBC BA15D Originally called the Small Bayonet Cap (SBC) type base, now BA15D, this is a 15mm diameter double contact cap with two equal/opposed bayonet pins on the cap and a single twin filament arrangement. Single filament bulbs for earth through one of the contacts rather than via the cap applications. Used in many bulb applications, but for head and spot lamp application, usually with a 38mm diameter clear glass globe. See Bulb Types BA15D SINGLE FILAMENT and BA15D DOUBLE FILAMENT, all with links to related product options. LED bulb options fitted with the SBC BA15D base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	P36T This base has a 22mm diameter cap fitted with a 36mm diameter plate - with one half-round locating notch – as the British Pre-focus base, BUT fitted with three spade contact terminals similar to the H4 connection arrangement. Twin filament headlight bulb. See Bulb Type P36T HALOGEN. P36T SB35 is similar but with a 35mm diameter turret on top of a 36mm diameter plate and we offer one bulb of this type here.
	T19 PX15D 25.1 and T19 PX15S 25.1 This base has a 15mm diameter single or double contact cap, fitted with a 25mm diameter plate featuring a single distinctive half-round locating tab. Twin or single filament. Tubular 19mm diameter (T19) glass. Motorcycle or scooter headlamp application. See Bulb Types PX15D 25.1 T19 and PX15S 25.1 T19, all with links to related product options. LED bulb options fitted with the PX15D 25.1 base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	P15D 25.3 This base has a 15mm diameter double contact cap, fitted with a 25mm diameter plate featuring three distinctive square-cut locating tabs and a single half-round notch. Twin filament. Usually pear-shaped 25mm diameter glass. Motorcycle or scooter headlamp application. See Bulb Type P15D 25.3 with links to related product options. LED bulb options fitted with the P15D 25.3 base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	BAX15D LSP and BAY15D HEADLAMP These bases are used in many applications but there are a small number of headlamp options. BAX15D is a 15mm diameter double contact cap with two equally opposed pins, though one pin is longer than the other. BAY15D is a 15mm diameter double contact cap with two pins opposed in the same plane, but with a vertical offset. BAY15D is more commonly found on Stop & Tail or Side Light & Indicator bulbs. In headlamp application, the bulbs have a twin axial filament arrangement with a bulb shield. See Bulb Type BAX15D LSP and BAY15D HEADLAMP
	H1 P14.5S This base features a 24.5mm diameter base plate with a distinctive slash-cut flat and one spade connection. Single filament. Car and motorcycle head and spot lamp application. Available in a wide range of voltages, wattages and specifications some of which are for off-road use only due to brightness and/or colour tint. See Bulb Type H1 P14.5S with links to all related product options of this type
	H2 X511 This base is a very distinctive flat blade, 19.5mm wide, with two square-cut notches and one round hole with 9mm diameter halogen-filled glass. Single filament. Car and motorcycle head and spot lamp application. Available in a wide range of voltages, wattages and specifications some of which are for off-road use only due to brightness and/or colour tint. See Bulb Type H2 X511 with links to all related product options of this type.
	H3 PK22S This base features a 24.5mm diameter base plate with two distinctive half-round cutouts and one spade connection on the end of a short wire. Single filament. Car and motorcycle head and spot lamp application. Available in a wide range of voltages, wattages and specifications some of which are for off-road use only due to brightness and/or colour tint. See Bulb Type H3 PK22S with links to all related product options of this type.
	H4 PX43t and H4 P43t P43T has a 43mm diameter base plate with three locating tabs - two 6mm wide and one 8mm wide. PX43T is the same but with two 6mm wide tabs and one 10mm wide tab. PX43T is used on motorcycles. P43T will fit into PX43T holders but not the other way around. Two square holes in the base plate between two narrower tabs. 38mm diameter turret with 23mm long flat above base plate. Three spade connections - one for neutral/earth and two for live, dipped and main beam. Very common on classics/halogen bulb upgrades. Twin filament headlamp bulbs are available in a wide range of wattages and specifications, some of which are for off-road use only due to brightness and/or colour tint. See Bulb Types H4 PX43t and H4 P43t with links to all related product options of these types. LED bulb options fitted with the H4 P43T base are also available here. Please check bulb dimensions to ensure that your lamps can accommodate them.
	H7 PX26D This base comprises a 34mm diameter round plate with 21mm long flat side featuring a square cut 8mm wide locating tab. 26mm diameter turret on top of the base plate. Two spade connections. Single filament car, motorcycle and commercial vehicle halogen headlamp bulb are available in a wide range of wattages and specifications some of which are for off-road use only due to brightness and/or colour tint. See Bulb Type H7 PX26D with links to all related product options of this type.