Precision Lightweight GPS Receiver
The AN/PSN-11 Precision Lightweight GPS Receiver (PLGR, colloquially "plugger") is a ruggedized, hand-held, single-frequency GPS receiver fielded by the United States Armed Forces. It incorporates the Precise Positioning Service — Security Module (PPS-SM) to access the encrypted P(Y) code GPS signal.
Source: Wikipedia — Precision Lightweight GPS Receiver (CC BY-SA 4.0)