... that stupid little rubber piece that the sensor slipps into and you ziptie to the fork?
Cateye's website only sells the full sensor kit, haven't found just the rubber part on any other website either. I swear I had mine in my hand in my room and was eaten between there and the back door buy a bunch of other parts I was carrying at the same time. Or maybe someone's got one stuck in the back of a parts drawer out there...? (a guy can hope!)