Well nothing compares to power extending/retracting mirrors, whether it be the TTT mirrors or the GM OEM. I have a set of used CIPA slip ons ... used about 4 times off my 03 I'd let go cheap as I installed the 03 OEM camper/towing mirrors. I also carry the 2003 GM OEM camper/towing mirrors. If your interested in either just PM me or see the vendor area.
I'm not sure what other slip-ons are available other then the CIPA slip-ons, not to say there aren't any others.
I'm not sure what other slip-ons are available other then the CIPA slip-ons, not to say there aren't any others.