These people are not even technicians and rather foolish to recommend an inferior device. These devices provide no thermal overload protection, and very poor power overload protection. If you live in a high power surge area like I do, you must be careful what you use to protect the compressor you are working on.
Manufactures of most of the modern, fractional, high efficiency compressors use either a PTC start device with external klixon, or a packaged device like the WR09X10106 which contains a waifer ptc device and a klixon, which provides a nominal drop out current of 20 amps. These compressors,( except GE compressors which are impeadance protected) draw extremely high current at startup and must be protected. They do worst case analysis and want to make sure the compressor will survive a power surge, or loss of cooling. Compressors I work on range from .15 hp to more than .5 hp. For these, the ptc device and klixon must be selected carefully to ensure reliable starting and proper overload protection.
In addition, the pinout of some compressors may not be the standard start pin on the bottom left.
I stock a good selection of ptc devices and Klixons, but recently, I have been using a lot of the WR09X10106 box devices.