I somehow ended up with 4 of these. I rarely need flash for my work and have some studio strobes if I do end up needing more light. I've used all of them with AC power (see below) and AAs. No broken battery doors or anything funky. They all have the auto thyristors, not the power dial. $80 shipped for them, plus two filter adapters, plus a pack of original Vivitar filters, plus a Vivitar specific AC adapter so you can keep popping one without breaking the bank, plus a Vivitar to PC sync cord.