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.

Raymarine
GD009 (M8 x 1.25 Male Thread)	C70  |  C80  |  C120  |  L750  |  RC425  |  RC435  |  RC435i  |  RL70  | RL70RC RL70C  |  RL70CRC  |  R70 Plus  |  R70RC Plus  |  R80 Plus  |  R80RC Plus RL80C Plus  |  RL80CRC Plus  |  SL70  |  SL70RC  |  SL72 Plus  |  SL72RCPlus SL520  |  SL530  |  SL631  |  SL770RC  |  SL755RC  |  SL760RC  |  SL1250RC DS600X  |  RayNav 300  |  RayChart -  520 Plus, 530 Plus, 620 Plus,  631 Plus 630  |  E80  |  E120
GD010 (M6 x 1.00 Male Thread)	DS400X  |  DS500X   |  A65
GD011 (M6 x 1.00 Thread)	Raytheon NAV398