Match up the dimensions of the raised hub on your block to the inside dimensions of the plier jaw (stated with each plier style). As various edgers use blocks from a range of suppliers, matching dimensions is the best way to determine the plier that is suitable for you. Every plier has a tension screw to adjust the grip on the block.
#WO2006V – Black Vinyl Handle, 15mm Round with Metal Cap
#WO2006F – Green Foam Handle, 15mm Round with Metal Cap