I called Laser Devices, Inc. 800-235-2162, list price $193. They referred me to a dealer - LaserKing 800-497-2041 LASTAC, $164.82. It clips on very easy and adds quite a bit of muzzle weight to the package. With it on it kind of swings like a shotgun - muzzle heavy - good for leading bad guys on the run? I still have not taken it to the range.
I got the P99 out to the range today with the LAS/TAC and the light acquitted itself well. In the low light of the indoor range I shot at distances of 5 and 7 yards, holding at chest level, using only the light as my point of aim. My groups were as wide as 5" with an occasional flyer when shooting rapid double taps and as small as 3" with more time and attention. So if I ever light up a bad guy at household distances . . .