The Allen 20mm Dynamic Flip Flop Block with A.677 Cleat features a relocatable sheave with two installation locations, dynamic bearings for superior load-carrying ability, and a removable design. It also includes the Allenite Cam Cleat, which is made of a lightweight and durable material for increased wear resistance. This block is ideal for halyards, pole launchers, and jib sheets with lower loading, while higher loading applications should opt for the A2123-77 version. View the complete dimensions in the provided PDF.