These bushings are for the 7mm Euro pen kit. And use the "A" sized mandrel shaft. Please be aware that if you use the High Precision shaft, you cannot get both the upper and lower barrels on that shaft at the same time.
These are the bushing I use myself. It is the only kit that I make without using the high-precision system. These bushings have the movable center band ring that enables you to turn the 7mm Euro kit without the aid of dial calipers. Turn the tenon on the upper barrel so that the center band ring just fits onto the tenon. I also like to turn a little groove at the shoulder end of the tenon so any excess glue will flow into that groove.
The bushings are shown as you would place them on the mandrel with the nib towards the left.