I actually bought a pack of the AG shields for my 2200 (I guess they came in 3's then). I never had a need to change it over the 2+ years I used the device and it cleaned really well. I found them the other day and trimmed one down to put on my 8125. That worked, but not as well as one that would be designed for the device so I'll probably end up shelling out for a set for my device.
Great shields and I highly recommend them, especially if you fall in the set of people who can't quite manage to change out their PDA every couple of months.
-Pete