Asics Knee Pad with Lycra
Asics Pad with Lycra
Asics Reversible Gel Knee Pad

This is a good pad for two reasons.  If you have wardrobe where a black pad would show through you can reverse it to show the white side out, and if you need more support at the knee it has a healthy neoprine sleeve to give you that extra support.

Asics Junior Gel Knee Pad