I've got skinny legs, and it doesn't matter how you strap a knee pad onto skinny legs. Criss-cross the straps? Tried it. Cross them the other way? Tried that too. Every single time I stood up, I was hiking my knee pads back up.
Pants with knee pad pockets helped, but then you're walking around all day with pads bulging out of your pants. And when the pants wear out, it's new pants and new pads.
One day, working on concrete, I looked over at the windows we were installing. Window manufacturers stick little foam pads between windows so they don't rub during shipping. I peeled one off, the adhesive was still good, and I stuck it on my pants. It stayed put, right where my knee needed it. The three guys I was working with that day got it right away.
That's how Z-Pads started: stick-on knee pads made from recycled foam, built to re-stick and last the workweek. No straps. No slipping. No bulge.
Mark Zeabin, founder, Kelowna, BC