1/10 the cost of a Hammer unit. As to the benefits, my jury is still out. Preliminary tests suggest that it helps some. The problem, at least with my unit, is that it exercises one bilateral muscle pair at a time, for 20 minutes or so. So a full EMS leg workout takes me over 100 minutes. I exercise my VLM and VMO separately to keep my patella on track. I had a miniscus repair done maybe 10 years ago, and minor residual pain from that seems less since I started with the EMS.
My unit only has a pair of pads, one each for left and right leg, etc. The Hammer units may have more pairs of pads. OTOH, one could buy 2 units like mine and do both the VML and VMO, then both the hams and calves, and cut the time almost in half. Which I might do if this thing proves a success.