In reply to Andrew Mason:
I have 16 CAMP orbit QD from Decathlon; for my sport rack.
There not heavy and the nylon sling is think enough to grab and dog on if you have to.
I have compared these with the Petzl Spirit Express QDs and they are very similar at half the price.
The only proble i found was that the ones decathlon sell are that they are all 11cm long; going over a roof can cause rope drag.
I solved this by buying a 1/2 dozen longer nylon sawn slings (Petzl Spirit Express).