The Thermal Weapon Sight is a selfcontained lightweight, compact, durable, battery-operated, infrared imaging sensor used for target acquisition. It can be used under conditions of limited visibility such as darkness, smoke, fog, dust and haze, and is effective during daylight hours. The MWTS and HWTS have the same design but the difference lies in the telescope and the software. The system comes with a MIL-STD-1913 rail grabber interface, including a vertical spacer. The MWTS can effectively engage targets out to 1,100 meters while the HWTS can effectively engage targets out to 2,200 meters. The U.S. Marine Corps is procuring both the Medium Weapon Thermal Sight (AN/PAS-13D (V)2) and the Heavy Weapon Thermal Sight (AN/PAS-13D (V)3).
The AN/PAS-13D (V) 2 can be mounted on the M240B Machine Gun and the M249 series. The AN/PAS-13D (V) 3 can be mounted on the M16A1/A2 Rifle, M4 series, M2 Machine Gun, and the MK19 Machine Gun.
These items are replacing the AN/PAS-13B (V) 2 Medium Weapon Thermal Sight (MWTS) and (V) 3 Heavy Weapon Thermal Sight (HWTS).