50mm Single Dynamic Cheek Block.The A2050C is a high performing ball bearing block, designed to eliminate friction and allow rope to run at great speeds. Ideal for use on Keelboats and Catamarans as a turning or leading block for most systems. Cheek Mouting - The A2050C comes with a cheek adaptor to allow mounting of our A2050 block to a flat surface. The adaptor allows for three fixings to be used to ensure a strong and reliable fitting to any surface. The chamfered shape of the cheek adaptor limits the chances of snagging. Bearings Ð Dynamic Blocks feature our patented bearing system which uses twin rows of stainless-steel ball bearings running on a stainless-steel rail. This provides a superior load-carrying ability and longevity when compared to other bearing systems available on the market.