From the manufacturer:
ES Bottle Capping Machines are very simple to operate and comfortable to use. They provide outstanding repeatable torque accuracy on screw and lug type caps from 10mm – 70mm in diameter. The torque output is easily adjusted by turning an external torque dial with your fingers. Featuring a direct plug-in cord, ES™ Capping Machines run quietly on standard electricity, making them ideal for use in places without access to compressed air.
From me:
This was one of the best investments I made early on. We were getting tennis elbow twisting caps onto our bottles. This worked perfectly. I hung it from a light chain from a girder, to the Balancer* to the Capper. I used this for 40 mm caps, but you can buy other size aluminum chucks, and rubber inserts (they last a good amount of time, but do wear out. They cost less than $10 to replace) to fit your size of cap. The aluminum chuck size is approx 55 mm. It twists in either direction. The retractable Balancer cord is approx 48 inches long and the tension on that is adjustable. The package currently lists new for $1085. Condition is very good, if not excellent.
Will consider returns within 30 days if this doesn't work as described.
see kinnexcappers.com for more info.
May also consider reasonable offers.