This PL universal mount is based on the universal 58mm thread system with a 3mm locating slot cut into the the mating Face .
The original design was made by Coooke in the days of the Cooke Varotal & cine Varotal Lenses. It has since been used on manytelephoto lens conversions .
Beware there are some variations in particular the lock down rings which generally come in two sizes long and short.
If in doubt measure the depth of the available thread on your lens and let us know we will endeavour to send you the correct lock ring (Default order the short one)
Rear Baffles- we can supply these but generally do not as they have the potential to cut off the image on larger format sensors.