No longer have a need for this, but served me well when I had a large weight difference between me and my climber. When not in use, was always stored indoors in a smoke-free and pet-free house. $65 PLUS shipping, OBO

Assisted-braking resistor to increase rope friction when there is a large weight difference between belayer and lead climber. In the event of a fall, the OHM increases the amount of rope friction so that a lighter belayer can hold a heavier lead climber without difficulty. 

• Ohm attaches at the first bolt in the safety chain; in the event of a fall, the rope is pulled into the device's braking unit and the fall is progressively arrested -With Ohm, belay normally with your preferred belay device; Ohm is not a replacement for a belay device 
• The Ohm makes it easier for a belayer to hold a fall and limits how high he or she is pulled off the ground; this can help reduce the distance a lead climber falls 
• Lowering a heavier climber is also easier to control 
• Ohm does not increase friction for the lead climber, nor does it negatively affect paying out the rope 
• For single ropes with diameters of 8.9 to 11mm 
• Recommended weight difference (lead climber > belayer): 25–85 lbs.; minimum belayer weight 85 lbs.