Used like a ladder jack in scaffolding. Holds a rail for stability - like a hand rail. You must supply a 2x4 or some lumber piece to stretch between two or more rail jacks. Makes for a more stable set-up than a walk board and ladder jacks alone.
Home Repair Resource Center
http://hrrc-ch.org/toollibrary/
2520 Noble Rd.http://hrrc-ch.org/toollibrary/
Cleveland Heights, OH, 44121
USA
(216) 381-6100