The original Fenix TK-21 has a number of quality features that sure the clone has not (one for all, Fenix UI with side mode button and forward tactical tailswitch instead of the cheap common 5 mode strobe driver) but the look is well replicated, with nice square anodized threads. It even sports the original TK-21 model name engraved.
At a mere $27, who is going to buy and test one vs the original?
