The Ratchet Hook is self-gripping and secures itself through the spring mechanism in the hook. Easily adjustable in height by pressing down the hook. Applicable with perlon wire 2 mm and steel wire 1.80mm. Max. Weight: 15 Kgs. - See more at: http://www.megawoodlarsonjuhl.com.au/product/13062-artiteq-ratchet-hook-15kg#sthash.IrXWwivI.dpuf