Retro Bike Bits SEAT POST BOLT, SADDLE PIN BOLT ALLEN KEY TYPE 27mm x 8mm QUALITY CRO-MO STEEL

Exactly what I was looking for at a very reasonable price and decent quality too.

Ad didn't exactly prominently point out that these are not a standard fits-most-bikes size. My bad for not checking more thooroughly, but still, they are not a size that fits either of my bikes, and I suspect is not a common size at all.Giving them 4 stars b/c that was my fault, but if you've not measured the diameter you need (most bikes use bolts that are thinner than these) then don't order them until you have.