I think David is having a joke - the KL5 makes the G2 larger.
The G2 can use the KL5 bezel. Bear in mind though that the heat produced from longer periods of constant-on will not spread as easily through the G2's Nitrolon body. I've not found it a problem in my normal use of the light though.
here is a photo showing the G2Z (could have been the G2) with different bezels on it.