A permanently affixed and travelling selector pin, car and weight plate selection mechanism for use with physical fitness equipment is disclosed including a segmented track and/or cut out cavern within the plate body for the car to travel within in either vertically or horizontally in order to select a different weight plate or cumulatively, more or less weight for an exercise. The selector pin and car mechanism features a selector pin which is not removable from the car and is inserted through the car which is contained by the track and or plate body shape and into a throughbore in the weight plate in order to engage with the selector stem.