Have them on my G27. Very easy to install and to sight. No problem with IWB carry in a Blackhawk! holster, however, the On button is in a bad spot for the retention strap on my OWB holster. Also have CT's on a S&W revolver. Just wish they were 20mw and green.I just ordered Crimson trace laser gripes for my Glock 27 dose any one have any experience with them pros-cons?