Abstract: A manual or vehicle propelled rolling distance measuring unit has a folding frame and support stand and is equipped on the handle portion of the frame with an electrically operated digital counter which responds to the rotary movement of wheel-mounted permanent magnets relative to a stationary magnetic switch. A rotational magnet shield is magnetically driven in one direction by a permanent magnet to a switch shielding position to prevent operation of the digital counter when the measuring device rolls in a reverse direction. The device can be used to establish the distance between poles in a cable television system.