I've been using these Proknee's since May. Wish I had known about them years ago. I can work for ~6-7 hours on my knees before it starts hurting. Way better cushion than the crap knee pads you get at homeless despot.
If I had to do it over, I would spend the $300 and get the custom fit knee pads. They are worth every penny.
ProKnee AP16 Kneepads 1" Foam: Amazon.com: Industrial & Scientific
If I had to do it over, I would spend the $300 and get the custom fit knee pads. They are worth every penny.
ProKnee AP16 Kneepads 1" Foam: Amazon.com: Industrial & Scientific
and yeah an old seat cushion is what I use when I'm working on roofs too.