I have two (2) units for sale.  $200/each or OBO. Both have been lightly used, like a few times a year.  Been stored for the past 4 years.  Always been in a climate controlled room.

The Safe-T-Grip travels on straight or curved climbs, and is designed to protect climber in the event o fa fall.  The sleeve has dual fall arrest capabilities.  The friction enhancing wheel provides constant contact with the rail as a climber moves up and down the rail. When properly used, the sleeve design assure each climber safe and reliable fall protection.  

These list new for over $1000.