The ATN MastClimber Bosun's Chair, formerly known as the TopClimber, is specifically designed for the solo ascent of sailboat masts. This unit features a hard seat with backrest and an integrated ascender system with one-way jammers on both the seat and leg straps, allowing the operator to work above the masthead without having to leave the chair. Constructed with anodized aluminum and stainless steel hardware, it is compatible with taut rope halyards ranging from 3/8" to 5/8". The MastClimber utilizes a leg-powered 'inch-worm' climb, eliminating the need for static lines, knots, or shackles, and can accommodate a maximum waist size of approximately 50 inches. This chair is in new condition and was taken out of bag once for dispay only... never used.   The bag shows signs of scuffs and marks but is great condition as well.  This unit is suitable for anyone needing to safely and efficiently climb masts without assistance.