They do not slip
and which I personally just go to snowboard very great find: the knee is covered not only from the front right but also the side of the schooner and protected.
At the last holiday (without saver) I tightened myself an ordinary bruise, with whom I had to fight many weeks. The schooners not even a bruise could be seen.
They serve their purpose so!
For me it was just a regrettable fact that I totally sweated under the gizmos. My long underwear was completely wet in the area where the schooner sat.
Also noticed a negative to me is that they (chemical) smell very strong. But it was unbearable. It would be better, but to let them air out after buying something.
As an extra thick I personally would not call the saver but ....
All in all, definitely a good value for money !!