The Harken 16mm Hook-In Halyard Block is the smallest in their line, making it ideal for high-tech dinghies with smaller synthetic control lines. It features a patented bearing system with stainless steel balls and a captive grooved race, capable of withstanding a maximum working load of 250 lb (113 kg). Part No. 391, with a sheave diameter of 16 mm (5/8 in), is designed to accommodate lines up to 5 mm (7/32 in).