NOVELTY - The system (100) has an expander and a shaft enclosure arranged to couple with the expander. An attachment element e.g. screw, is arranged to couple the expander with the shaft enclosure and non-permanently engage a golf club shaft (110) of a piece of equipment, without modification of the piece of equipment. A cap is provided with a side portion. A grip is arranged to engage the side portion of the cap and roll down the cap to enable the cap to be exposed, without removing the grip. The shaft enclosure is arranged to non-permanently couple the cap.    USE - Motion capture element mount system for mounting electronics e.g. passive or active radio frequency identification (RFID) tag, on a sporting, exercise or medical rehabilitation equipment e.g. golf club, tennis racket and weight training bar (all claimed), during competition by a golfer.    ADVANTAGE - The grip can be made to roll down from sides of a motion capture element to enable the motion capture element to be accessed, without removing the grip from the shaft. The system enables a mount to hold electronics and/or a visual marker, without modifying the equipment. The system can be flush-mounted with a normal end of the equipment or can have desired length of extension from the end of the equipment. The mount is separate from the electronics, so that an electronics package can be easily removed and replaced or the battery can be easily removed and replaced, without any tools. The system can utilize a battery coupling that attaches the battery to the shaft enclosure such that the battery does not fall out, unless intended, when the cap is removed, so that spring-based electrical contacts prevent loss of electrical conductivity even under high acceleration. The grip is rolled back over an angled area and onto side portions of the cap so as to enable an end of the cap to be seen through a hole in the end of the grip, and enable the grip to provide extra support for the motion capture element.    DETAILED DESCRIPTION - The equipment is a piece of sporting, exercise or medical rehabilitation equipment, golf club, tennis racket and weight training bat.    DESCRIPTION OF DRAWING(S) - The drawing shows a cutaway view perspective view of a motion capture element mount system mounted in a golf club shaft.    Motion capture element mount system (100)    Golf club shaft (110)