Static electricity adjustable pulley "PR DV" and "PBR DV" are designed for adjusting the pitch diameter. 

A flange is tightened onto the threaded hub using screws. The movable flange is equipped with fixing screws for attachment to the required position. It is applicable to Z-SPZ-3V, a-SPA, b-SPB-5V, and C-SPC V-belt pulleys. 

This is the description information

Adjustable pulley type 

"PR DV" with a hard hub 

The "PBR DV" used for installing the cone sleeve