Antal OPF series is a new light, strong one piece frame block, without pins or screws. It is a hard black anodized, Teflon coated aluminium frame. The sheave rotates on a hollow pin with the line passing through the pin’s centre. This type of block reduces the height of the line of the deck and the side loads on the block. The line position and its direction to the winch does not change even if the line is off centre.