The HTV3 and HTV4 sold on Amazon are fine and are usually about $30. I have three of them, one of which is stainless steel, and all are very comfortable.
All knock offs. Have never seen an imitation with comparable quality. The material is that different.
I am in a stainless steel Nub, it is comfortable and I have never been able to remove it without the key. It has been modified it so that TENS's leads and pads can be used to edge and apply corrective impulses if KH desires. Love the pictures of the devices.
If manufacturers priced more reasonably and perhaps sensibly they would not so easily be undercut by so much or so often. When buying a non-original you do have to be wary of the workmanship which is not so much of a problem these days and be wary of what the materials might be if not actually stated... again not so much of a problem these days. Like the Japanese decades ago the Chinese have become every adept at emulating and attempting to improve upon western goods whilst charging much less. I won't go into the why here. def an off topic discussion. I had HT fakes in steel and plastic I found no fault with either re materials and workmanship they just were not for us. For instance there was no way to effectively and comfortably accommodate my PA let lone utilise it for added security