Mine look a lot like the Rolson pads that hammered posted, however, mine do NOT stay in place very well, at all. Like T-hound, I usually only kneel on my right. The pads Jeff posted look pretty good, but, the straps leave a lot to be desired.
dogpound, let us know how the pads you linked to work out. The wide bands on those look like they might prevent slipping down while walking or shifting out of place when kneeling.
Edit: hammered, the Rolson brand appears to be available in the the U.K. only. Shipping might make them costly.