The cheekplate revolves around the sheave axle allowing the block to open; a safety ball prevent the block from opening and an adjustable screw allows to set the ball on locked position. There is a becket for the “hanging line”. Material: sheave with composite fibre main bearing and double side ball bearing. Hard anodized and teflon coated Aluminum cheekplates with side rubber protections (yellow rubber on the revolving cheekplate).