Silva Thumb Plate ARC JET

"The thumb plate on our Arc Jetcompasses is removable and an additional thumb plate replaces the worn or lost. The thumb base plate of the Arc Jetcompasses has a unique design with a recess for perfect contact between thumb and map and an attachable thumb plate for those who prefer the more classic thumb grip. Simply slide the thumb plate onto the base plate with a click and try out what you like best. The thumb plate fits all Arc Jetcompasses with the exception of the Arc Jet C."