This Wire Cheek Block with Fasteners by Harken is designed for use on boats of all sizes to carry wire halyards and high-strength control lines with ease. With a Sheave Ø of 25 mm (1 in) and a weight of 35 g (1.25 oz), it can handle lines up to 4 mm (5/32 in) in diameter and has a maximum working load of 454 kg (1000 lb). The fasteners, in 5 RH mm (#10 RH in), are included and the maximum wire diameter it can accommodate is 2 mm (3/32 in). With a breaking load of 907 kg (2000 lb), this block is strong and reliable for all your boating needs.