I have both the Thorfire TK01 and the Olight i3E EOS and the TK01 is a nice little light, (I also use it with a 10440), and even has a slot for a tritium tube on the end.

However as jerm03 states the Olight i3E EOS is a TRUE keychain light. It’s about 3/4 the size of the TK01 and the twisty action is smooth as silk. The TK01’s twisty action is rough and is basically a 2 hand affair.