Weapon lights and weapon light systems, including Surefire, Streamlight Tactical, Trijicon, Ameriglo and more.
Here are some links to the top selling and most highly rated pistol weapon lights:
Surefire X300U A LED Handgun Pistol Light
Surefire X300 Ultra B LED Handgun Pistol WeaponLight
LAPG SlideRail XWL Tactical WeaponLight
Streamlight TLR-1 WeaponLight
Streamlight TLR-1 HL Weaponlight