Axle Sleeves are available as 3 part sets. All three parts are the same OD and different on the ID:

1. One is non-threaded. It is used in the middle of a dual leg setup. 
   
2. The second has a recess for the Allen Bolt Head. It is used in a dual leg setup.
   
3. The third is threaded on both ends. It is used by itself for single leg mounting (shown below). It is also used in dual leg mounting on the outside.Get the complete set including all 8 sets (24 sleeves) listed above.

Complete Set 

TSDY FAMS01 20-32mm

TSDY FAM20 - 20mm
TSDY FAM22 - 22mm
TSDY FAM25 - 25mm
TSDY FAM26 - 26mm
TSDY FAM27 - 27mm
TSDY FAM28 - 28mm
TSDY FAM30 - 30mm
TSDY FAM32 - 32mm

 OR  Most forks require two different diameters to mount a pair of fork tubes.

 Here is a cross section view of a Dual Fork Leg Setup.

Note - The Upper Dual Fork Mount is required for dual setup.

 SINGLE FORK LEG SETUP

This is a combination of:
Lower Fork Base - TSDY FAMB01 and
a single Fork Axle Sleeve  - TSDY FAM Series

DUAL FORK LEG SETUP

This is a combination of:
Lower Fork Base - TSDY FAMB01 and
two Fork Axle Sleeve Sets - TSDY FAM Series (two, because the left and right are usually different diameters).

Race Tech Shock Dyno Mounts for CTW and Roehrig