SIRUI MP-20 quick change base Acra Swiss compatible Quality made by SIRUIThe SIRUI quick-change base MP-20 fits all tripod heads with interchangeable base and a 1/4 inch or 3/8 inch thread (adapter is included). However, monopods can also be equipped with the quick-change system.The Safety Lock System prevents the quick-release plate from accidentally slipping off and 3 leveling levels allow exact alignment. The clamping device is also compatible with the Arca Swiss System and allows the use of various plates.