The little black compressor (which I reference as GX CS1- clone) are sold under numerous labels, there are Yong Heng and Yong Heng clones, plus a bunch of others.
The GX CS1-type use an electric motor and gear reduction unit that looks like GX CS2 & GX CS3, however the compressor section is very different.
Yong Heng and various clones look similar from the outside but the high-pressure section can be quite different.
The remainder of the examples are unknown to me, so no idea about their construction.
I have taken photos of several types of compressors and these can allow various compressors to be compared. Perhaps we should start a thread to show the internal construction of some of the compressors on the market?
As for which compressor to buy, that depends on one's intended usage, budget, amount of use, and vessel volumes to be filled.
I started out with Yong Heng clones and bought some Yong Hengs, (5 in total) added some small bottles, moved onto a 45-minute SCBA tank, then replaced all of YHs with a GX CS3 and a Nuoge (GX CS1-type) which is my backup in case the CS3 fails at the range.
I shoot about 25,000 full power .22 pellets per year, on a one-day-per week shooting schedule.
I shoot at our club's range where we have a shooting shelter, benches and AC power. The GX CS3 is so much simpler and more portable, without the need to fill a tank/SCBA bottle that I wish that I had begun with that system.
We have had a couple of power failures at the range, so I powered the CS3 from a vehicle. I couldn't fill my guns for a 6-1/2 day of shooting, from one 45-minute SCBA, so would require (2) and also transport high pressure vessels in the passenger compartment of a vehicle, which I find unsafe.
The point that I am attempting to illustrate is that the blend of factors needing to be appreciated will make someone's ideal solution, someone else's worst possible choice.
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