Its a gamble on anything that relates to the engine running.
We have found some of his items to be worthy. By trial and error amongst hundreds on various forums.
I can give good marks to the locking fuel caps, gear shift knobs, expansion tanks, mk2 relay shaft. For the money.
In a lot of cases, you can get better quality at equal prices from places like AutohausAZ and RockAuto.
Everything from Prothe is no-name packaged in floppy boxes.
Its all made to be cheap, thats why it is cheap.
Sometimes that is good enough for certain people on certain cars.