Fsa gossamer sb20 seatpostour high tech manufacturing processes let us bring the 6061 t6 aluminium afterburner stem in at a low 144g 100mm very light for a mid range stem the raw material is 3d forged and then cnc machined into the final shape features material al6061 tube with forged alloy head clamp 1 bolt nano adjust saddle clamp for simple set up finish sandblasted black with polished black anodized setback 20mm weight 318g diameter 27 2buyfsa componentsfrom chain reaction cyc