I don't need a 7mm often, but for when I have a French thingamabob, I have a 7mm socket hex bit that lives with my socket set, so I always know where it is. Loose Allen wrenches have a way of walking away from me, so I like having the odd one truly be the odd one out.
https://www.autozone.com/screwdriver...d=OSA:US&gQT=1