Which are the best knee pads for gardening?

Which type of gardening knee pads are the best? My knees are constantly aching when I do my gardening.

Any type, really. I find it hard to believe there would be much difference is the ones available. I see construction workers with those plastic shelled ones that are padded on the inside, I bet those would work, since construction is probably as demanding or more demanding than gardening work.

Best,

thedude