The compactSchwank model features their "whisper-jet" burner for quieter burning. They are available in Europe as well as North America and are backed by a very good guarantee.
The RH model is a basic tube heater that is backed by a good warranty.
This brand is a division of GAS FIRED PRODUCTS INC. The COLD BLOCKER (CB) units are available in four sizes from 20,000 to 50,000 btu/hr. The 20,000 btu model is smaller than most brands offer so can be a better option for smaller garages. Their website is not much help and does not have a stated warranty policy.
The SIR series offers compact tube heaters in either straight or "U" configurations. They offer optional outdoor combustion kits but the warranty is not as good as some other brands.
This brand is made in Canada. The SERIES GR heaters have balanced flue (sealed combustion) and are available in two sizes. The SERIES U models are available as either vented or unvented and the TXR model offers two stage operation. The units are backed by a good warranty.