Rst steerer tube

[Ferry]

I am looking for a one inch threaded steerer tube. RST supplies these but I can not figure out if these are tapered at the bottom or if these are 25.4 mm for the whole length of the steerer?

Has anyone used these on a Bontrager composite fork? I want to replace a non threaded steerer.

 

[eshew]

The RST steerer tubes fit into a Marzocchi Z2 bolt on crown if that helps. The RST tube I bought came with a slide on adapter to mate to the 1-1/8" crown.