Zelo Jersey sizing help

luv_shimano

I've got my eye on the tetris cycling jersey. Does anyone know how they come out in terms of sizing?
I always find jerseys either to be too big or too small? I'm 5ft 10 but have a small torso which doesn't help. I prefer something which isn't flapping around but at the same time I don't want it too short revealing my builders crack

I was edging towards a medium but any help from anyone who owns one would be great.

Cheers

luv_shimano

Anyone?