Ronstan Orbit cheek block 40 mm. auto-ratchet rightom

Up to 14:1 holding power - highest available! Smooth easing of sheets . Clockwise rotation Fully automatic, load sensing ratchet engagement Recessed underside to suit curved mounting surface Low mounting points for maximum strength1; Smooth Easing of sheets With auto models the sheet runds out smoothly and freely as soon as the ratchet mechnaism disengages.; When engaged, and with manual models, the sheave cross-hole geometry eliminates the 'shuddering' ease-out that you can expect from traditional v-groove ratchet blocks ; * Recommended fasteners - 2 x 4mm (5/32") counter sunk head screws