Belay Device Care and maintenence

Question
Hi i am doing a paper and presentation for my intro to rock climbing class and i am doing the paper on belay devices.  I was just wondering what is your favorite belay device and also how to care and maintain them (and signs of when to retire them) thanks!

Answer
Steve--here's a review:

(1) I usen a grigri for sport climbing and a ATC-XP for trad climbing.
(2) The only belay/rappel device I ever retired is a figure used to rappel---I have retired six or eight of them of the years---when they get 2-3mm grooves--out they go.
(3) I imagine grigris could grow a significant groove--and then I would retire them.
(4) When you buy a device, don't through away the instructions---read them and save them.
(5) The only thing I do to maintain them is to inspect for cracks and grooves, and to clean grit off of them.

For more on climbing safety, please see, my book, "Ultrasafe, A Guide to Safer Rock Climbing," available at Amazon.com.

Good Luck

George Allen