Plain Kalloy.. made in all diameters ..7/8"/ 22.2mm at the top portion.
nicest micro-adjust stepless 1 bolt I've found
is actually the Saddle clip Brompton makes , AKA pentaclip, they're $30.
the multiplate clamping system reminds me of motorcycle clutches.

some saddles you see the rails from the sides , and the underside of the seat gets close..
Race Face has 1 bolt that clamps from the side, angle is a separate bolt,
it grips a clamp band around the seat post. a clever design.

others the flaps down the side of the saddle make adjustment difficult any where other than below.

Traditional 2 bolts on the top Campagnolo seat posts were developed when Brooks was the saddle.
the combination is perfect.