Looks more like a torx than a flat head 
Pssst… it means the top of the screw is flat lol not the type of tool you need.
lol. I figured that 
Not even sure they still make flat head screws. Those things SUCK!
Well that’s just great, now the Russians have our technology.
Don’t worry:
In Soviet Russia you don’t screw deck, deck screws you!
But seriously the first thing I looked for was the size of the screw. #6 #8 #10 1/4" 5/16"… And there was nothing. It took looking up a post on the Homely Despot to get a link to the specs. Keep in mind that the representative that responded didn’t just give an answer or an actual link to the info the customer wanted; they got a general “it’s in the technical pages on our site.” Which as you can see, wasn’t hard to post.