In climbing, cord and webbing made of combinations of UHMWPE and nylon yarn have gained popularity for their low weight and bulk. They exhibit very low elasticity compared to their nylon counterparts. Also, low elasticity translates to low toughness. The fiber's very high lubricity leads to poor knot-holding ability, and is mostly used in pre-sewn 'slings' (loops of webbing) — relying on knots to join sections of UHMWPE is generally not recommended, and if necessary it is recommended to use the triple fisherman's knot rather than the traditional double fisherman's knot.