I have mounted it on my AR15. It is super light. I am very happy with the light output. I love that it uses AAs. I sold my TLR-1S today after playing with it. I will be buying a second one in May for my birthday gift and a nice Kaluban holster for my G30 with it.
One direction is a pressure switch. You can activate the strobe. The other direction is permanent on. The middle is off.