I received one of these in the Tandem-X kit. It's a really simple device so there's nothing in there that can fail except batteries that eventually die. I have used alkaline and rechargeable lithium batteries (1.2V each) with repeated success. The safety key is spring loaded and it requires a firm hand. I wish the clips at the end of the cable were a bit more robust. Something like alligator clips would make it easier to clip onto the igniter leads. AA batteries are cheap and easy to get, especially in bulk.