The finish of the plastic is a bit rough as can be expected at this price, but all the parts still fit on each other perfectly. The important thing is that the contacts are of good quality and the screws accept proper tightening torque without thread damage. This is probably the reason this plug seems to be VDE certified, which is a good sign.
The screws in the contacts press on the wires directly, so my recommendation is to use terminating sleeves on stranded wires to make a good contact, especially if there is the possibilty of higher current draw. (If you're not experienced in the field of electrics, keep in mind that poorly made contacts often will heat up at higher loads, and in the worst case they may catch fire!)
The screws on the strain relief inside the plug are partially threaded which enables proper clamping on the cable. Also the screw on the cover is partially threaded to seat the cover properly. The cover also locks in the contacts which can be pulled out for (dis)assembly if needed.
Toolingwise, all the screw heads are combos of Pozi-Driv PZ1 and flat-head, PZ1 being the universal fit for them all.