This Fotga brand 0.8MM PITCH GEAR for follow focus can be used with all standard prime lenses.
It is completely compatible with Fotga DP500IIS & DP3000 Follow Focus(Can mount on the DP500IIS directly) and also fits to DP500II (should use an adapter and longer thumb threw as the pictures shows,which are included) follow focus series.
M0.8-38T,38 teeth, 0.8mm pitch,and diameter is about 28mm.