UNIFIBER ADJUSTABLE COLLAR SDM HD EXTENSIONAdjustable collar for SDM HD extension which can bear the highest possible downhaul loads without deformation. The "open, twist & slide and twist and lock" functionality let's you set the collar quick and easy. Pros Open, twist & slide and twist and lock functionality Collar for heavy duty use Cons For some users more less intuitive to operate While derigging make sure the hinge part can not get stuck behind the mastsleeve Rubber O ring will wear out