The Lexus RX450h side marker requires a 168 bulb size for the lighting component. Data for the specific bulb requirements covers the period from 2021 through 2021.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 168 bulb is the most frequently specified size across the Lexus RX450h side marker positions. It follows the ANSI standard recognized in the US and Canada, and it is a miniature wedge bulb in the T10 form factor rated at 12V and 4.9W.
The 12961 is a Philips part number designation for a T10 miniature wedge bulb with a W2.1x9.5d base, rated at 12V and 5W. It is specified for the front side marker on the Lexus RX450h for the 2021-2022 model years.
Both the 168 and 12961 share the T10 wedge form factor, meaning they are physically similar in shape. However, the 12961 carries a slightly higher wattage rating of 5W compared to the 4.9W of the 168, and it is identified by a manufacturer-specific part number rather than an ANSI standard designation.
The front side marker position on the RX450h uses the 168 bulb for the 2010-2012 and 2016-2019 model years, while the 12961 is specified for 2021-2022.
The rear side marker position on the RX450h uses the 168 bulb exclusively across all listed model years, spanning 2010-2015.
The W2.1x9.5d base noted for the 12961 is the IEC designation for the standard T10 wedge base, describing the contact width and pin spacing. This base type is the same physical configuration shared by T10 bulbs in general, including those sold under the ANSI 168 designation.
Because the 12961 and 168 share the T10 wedge base, physical fitment in the socket is generally compatible. However, the wattage difference and the manufacturer-specific versus ANSI classification mean they are not formally interchangeable designations, and substitution depends on whether the housing and circuit tolerances accommodate the minor wattage variation.