JSpacers are specifically molded o-rings that fit perfectly between a switch shaft and click jacket and magically turn clicky switches into tactile ones. Traditionally these have been used with Outemu Blues to make a famous mod called a Jailhouse Blue switch.
Though some have thought them to be lost to the sands of time and resorted to regular, circular o-rings, we've been able to acquire authentic and genuine JSpacers from the former TheVan Keyboards.
These come in packs of 110 each.
Note: These will work on any clicky switch with a click jacket, which is most of them except for Kailh switches, which use a click bar.