Collection: Interior & Parking Lights (W5W, T10...)

W5W and T10: why two names for the same bulb?

This is the most frequent confusion in this part of the catalog: W5W and T10 refer to exactly the same bulb. You can buy either one interchangeably — they are two parallel designations for the same physical format.

• T10 designates the physical format: T for Tubular (cylindrical glass shape), 10 for the glass diameter in mm.
• W5W is the CEE electrical designation: W for Wedge (cap without bayonet), 5 for the power in watts, W for the tungsten filament.

Manufacturers use one designation or the other depending on the markets. If you find "T10 W5W" on packaging, it's just the two designations side by side — not two different bulbs.

W5W / T10: what uses?

The W5W (T10) is one of the most universal bulbs in a vehicle: front sidelight (position light), license plate light, trunk light, glove box light, storage compartment light, side marker lights on some sedans, and even some dashboard indicator lights. The wedge format without bayonet allows for very simple replacement: just pull to remove and push to insert.

BA9s: the quintessential dome light base

The BA9s (T4W) is a bayonet base with a 9 mm diameter. It is mainly used in round dome lights, traditional interior lighting, and indicator lights. Different from the W5W (which is a wedge), it requires rotation to insert into the socket. Available in halogen (4W) and LED (4W equivalent with reduced consumption).

W16W and T15: reverse and rear position lights

The W16W has become the standard for reverse lights on European vehicles since 2005. It's a wedge format similar to the W5W but more powerful (16W). The T15 (WY16W) in orange is used for some position and reverse lights on specific vehicles. Switching to LED provides a clear visual gain and faster response — particularly useful for reversing.

Switching your sidelights to LED

Switching to LED for interior lights is legally free and has no impact on the technical inspection (provided that the regulatory color is respected for exterior sidelights and the license plate). Advantages: purer white light, 5 to 10 times longer lifespan than halogen, 80% less consumption.

On vehicles equipped with the CAN-Bus system (especially high-end German models), a canbus LED with integrated resistor is recommended to avoid the "bulb faulty" error message on the dashboard.