Adjustable 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 over time (collar can be used without but will need to be closed manually)