Triple Block Maximum Working Load: 1650 lbs Breaking Load: 3310 lbs Low friction 2-stage ball bearing system provides consistent performance over the full load range. Hight static and dynamic load capacity. Light weight. Head posts of swivel blocks can be locked at 0 or 90 degrees. Cheek cut-outs for easy bearing maintenance. Removable becket pins allow lines to be spliced prior to fitting. Blocks can be dissasembled for servising or customisation. Max line diameter is 10mm (3/8"). Pin diameter on the post is 6mm (1/4") except for light load block, which is 5mm (3/16"). Great for: mainsheet and spinnaker sheets on sportsboats to 33', halyard, vang and backstay applications on boats to 30', and various control line applications on larger yachts. Pivoting lead blocks maintain alignment and keep lines as close to the deck as possible. Cheek block has through-hub mounting for maximum strenth and the singles can be stacked to create a double. Carbon black Acetal ball bearings. UV stabilised Acetal Sheaves. Alloy cheeks. Shackles are forged 316 stainless steel.