Price: $155.00 Item #KA-019EOS: Kaisei 019 main tubeset, 4130 .8/.5/.8 oversize tubing. This includes head tube, seat tube, down tube, top tube and steerer tube. You must choose chain stays, seat stays and fork blades as separate items, but they are included in the tubeset price.Description---O.D.------Wall------Butt/taper/center/taper/butt------lengthTop Tube 28.6mm .8-.5-.8 110---50-----290---50--110 610mmDown Tube 31.8mm .8-.5-.8 180---50-----280---50----80 640mmSeat Tube 28.6mm .8-.5-.7 140---50----290---50----110 640mmHead Tube 31.8 1mm N/A 210mmRecommended seat post size 27.0mmNote; this looks like double butted on paper but what you can't tell from the numbers is that there is a constant taper from the "obvious" butt to the thinnest center section and then a constant taper back out to the butt at the other end of the top & downtubes. This constitutes the quad butted feature. The seat tube is a true double butted tube.