The Harken Bullet Cheek Block works well for control lines up to 5/16 in. and can handle a 300 lb working load. This low-friction Bullet block leads control lines aft but yet are compact and lightweight, with fast trim and release under high or low loads. The Harken Bullet Cheek Blocks use roller bearings to carry higher loads and feature Hardkote-anodized Teflon impregnated aluminum sheaves for strength and corrosion resistance.
used this on to help furl my sail on my hobie sport