Must use the correct size, it doesn't stretch much. Had to urgently get some 10mm because the swirl pot was 10mm not 8mm as the rest. Important to get the right size clips, and plastic ends. although H16 fitted the 10mm ok. I found that the best way to cut hose was with a tight strip of sticky tape, then a Dremel type cutter disc, making sure the direction of rotation is inwards, then the stainless braid "bends" inwards.