Currently, these are compatible with the Sanwa Denshi JLF and Hori Hayabusa joysticks. 

Recommended Accessory:  PHREAKMODS Link Lanyard

Seimitsu Version (for LS-32 or LS-56, 58, 60, 62)

Information below is from Phreakmods.com

The Link is a new JLF shaft design that is purposed to allow easy storage for all kinds of players. The casual players looking to save a little space, and for traveling tournament players who need every inch when cramming into a full car.

The new design is a two piece stainless steel construction. When in place, the Link is identical in height, allowing for you to drop it right into your current arcade stick that has a Sanwa JLF and feel no difference. The diameter of the center collar is perfect size so that you can keep your current dust washer, however the shaft cover will have to go!

Compared to the original shaft, the Link is nearly identical. The few base changes are the collar locking/unlocking mechanic and the hollow construction to cut down on any added weight.  This newer production is a solid core, therefore does not allow LED pass thru.  Please make note of this.

Another key difference is in how the top is changed out. In the old design you had to utilize the flat head screwdriver slot to get ample torque to tighten the top enough not to loosen. In the new design, the center of the top section has been keyed for a 3mm hex bit, allowing for a more streamlined approach.

Variants

Sanwa | Hori - this type fits the Sanwa Denshi JLF series and Hori's Hayabusa joysticks

Seimitsu - this type is suited for the LS-32-01, LS-32-01-SC, or the LS-38-01-SC.  Note that you will not be able to utilized the dust or shaft covers on the SC variants.

Images:  Link images courtesy of Phreakmods, images of the Hori HRAP4 Kai modded with Phreakmod Link and Seimtsu pushbuttons belong to Arcadeshock.  Do NOT use without prior written permission.

ACCESSORY:  We highly recommend bundling this with the official Phreakmods lanyard, which has a metal stub that allows you to connect the Link to this for safekeeping around your neck.  This way, you'll always know where your joystick is without having to dig through bags.