Designer Gripsare built to last a lifetime, but I have to say thatI do see a certain humor in offering a lifetime guarantee when I have stage 4 cancer. So here's the best I can do under the circumstances:
For as long as I am able, any of my grips that fail to withstand the normal wear and tear typical of firearm use will be repaired or replaced at no charge.
Update 2021: I have now been 7 years without any sign of the cancer returning. The Doctors tell me that, at this point, it is extremely unlikely that it will. Maybe "my lifetime guarantee" will last longer than originally thought.