The base is slightly shorter and the ceramic base is not chamfered as shown in the Revain drawing, resulting in an electrical contact in my light compared to the Phillips T4 sold by Home Depot -Lightbulb is prevented right. Extending the center contact of the lamp by adding a drop of solder provided functionality and so far the brightness and color have been on par. These bulbs may have worked by bending my light's center pins, but due to their location, that wasn't possible.