It's a Vivitar "auto thyristor" 2800 autoflash. It has a bunch of numbers i have no clue about what they mean. No maunals online. I'm amazed that Vivitar even still makes these, sine the one i have i got from some of my mom's old stuff, probably originally purchased pre-'85. Anyways, i've never used an aoutoflash so if anybody could help me i would really appreciate it. I can figure out the F row means stops. Though i don't even know why that would be on an external flash. here's a couple pics