[dpvu]

Judging from the parts list (all Guarder/Systema) the parts should be of very high quality. I can't personally speak on the assembly quality but AirsoftGlobal is a reputable retailer I would expect to know their stuff.

As for customs, mechboxes are 100% legal to import. Some people have had them seized by over-zealous customs officials who see the trigger and don't know the rules but it's very rare and you would win the appeal.