16mm Block with SwivelThe 16 mm is Harken's smallest block. It is perfect for small synthetic control lines found on high-tech dinghies. The patented bearing system uses stainless steel balls in a captive grooved race and has a 250 lb (113 kg) maximum working load.. Specifications:. Sheave: 16mm / 5/8in.. Length: 46mm / 1-13/16in.. Weight: 18g /.63oz. Shackle pin: 4mm / 5/32in. Maximum line: 5mm / 7/32. Maximum working load: 113kg/ 250lb. Breaking load: 339kg / 750lb