Instructions:
(a) Remove one factory knob from either side of unit.
(b) Turn key clockwise and remove from lock.
(c) Screw GPS/Sounder lock into female thread until tight.
(d) Insert key and turn counter clockwise.
(e) Knob will spin freely when locked correctly making it impossible to remove..
Note: Lubricate often and record key number for replacement keys when lost.

Garmin
GD002 (M6 x 1.00 Male Thread)	Fish Finder - 100, 100 Blue, 160, 160 Blue, 240, 240 Blue, 320C GPS - 65, 120, 120XL, 125S, 126, 128     GPSMAP - 130, 152, 162, 180, 182, 182C, 185S, 188, 188C, 192C, 198C, 205, 210, 215, 220, 225, 230, 232, 235S, 2006, 2006C, 2010, 2010C, 2106, 2110, 2206, 2210, 3006C, 3010C, 3206, 3210, 135 Sounder, 168 Sounder, 238 Sounder3010C, 3206, 3210, 135 Sounder, 168 Sounder, 238 Sounder
GD020	GPSMAP – 172/172C, 178/178C, 292, 298, 340C, 392, 398, 489C, 492, 498C
GD021	276C,  376C