Fotga Upgrade DP500IIS Quick Rlease Dampen Follow Focus A/B hard stop for 15mm Rail DSLR Rig 5DII III IV 7D D90 D5 D500 D850 DSLR Camera, A7 A7R A7S II III A9, GH4/5/5S DP500IIS follow focus is upgraded based on the previous DP500II version I follow focus.More elegent apperance,more practicable. Quick-release version,easily attach and detach. There is an improvement on its inner structure to reach a high level in this field,which permits much less backlash,even better than the previous DP500II follow focus and most follow focus on the market.There is also a button downside can adjust the tension of of the gearbox to reach 2 dampen level. This improved Follow Focus Integrated with A/B Hard Stops which have easy begin/end setups for fast repeatable racking between two points, and make focusing lenses that have no hard stops (such as Canon EF lenses) much easier. Further more,the gear wheel on it can be detached and insalled in other side,which makes it suitable for both left-hand and right-hand photographer. The white mark ring is made of magnet material.It can be detached or attached very easliy and quickly on matel-made follow focus.You can also buy additional mark ring. The particular part of this follow focus is it can use different size gears.It can work with 3 different size gear to meet your different need with various lens: 38T (38 teeth) 0.8mm pitch,diameter is approx.28mm (not included) 43T (43 teeth) 0.8mm pitch,diameter is approx.31mm (included) 65T (65 teeth) 0.8mm pitch,diameter is approx.49mm(not included)