I have a protek 506.
Yep, it does indeed have a 20A range. (marking says max 30sec)
I damaged mine running it at 10A for 5min continuous. A small signal diode got too hot and went open. Was an easy fix.
The construction inside is pretty old school. Two boards with lots of passive stuff.
As far as meters go, it does work fine, although the inductance/capacitance ranges aren't very useful.
The main issue i have with it is the auto power off current, it uses quite a bit and runs flat pretty fast.
Using the power button is fine though, that's a proper toggle switch.
The continuity range is pretty slow, 300ms or so, but that's usual for cheap meters.