The Arri standard mount requires a very specific type of mount that uses a "tab" to prevent the lens from rotating inside the PL mount adapter. Duclos Lenses offers an Arri Standard - PL Mount adapter made from stainless steel. For use with lenses such as Cooke Speed Panchros or vintage Zeiss primes. Tuning adjustments are usually required for this mount to work properly. Therefore this product is for in-house installation or available to authorized partners.