Warmbac Warmtex adjustable knee pads
High spec and very tough knee pads. Outer surface coated with very durable warmtex material. Inner surface is higher friction double diamond neoprene. Fully adjustable Velcro straps provide a surprisingly solid attachment - also proof against muddy caves. Good for those with odd shaped legs, divers wearing drysuits, and those with bad backs who can't be bothered to fight kneepads over wellies, every trip.
Top tip: glue a *small* patch of spare neoprene (part of an old wetsock, perhaps)on the inside of the kneepad, as soon as you can after purchase. Just enough to cover the lower joint, not so much as to cause the kneepad to become inflexible and gape at the sides (which would allow gravel in). Your knees will love you for it in future years!