vernier pulleys

[greyjasper51]

im looking for a specific type of vernier pulley that im sure i have seen on here but i cant find it, there not the catcam true locks, but its a similar principle only rather than using the pin to set the position and using the bolts that lock it in position, these used the bolts in the similar fasion to the pin for the catcam ones... so there is no chance of them sliding unless the bolts break...

im trying to explain it clearly but maybe im not doing so well...

any help appriciated and pictures would be of great help


many thanks