These spacers are designed for situations when you have table system with 19 mm diameter holes, but the thickness of the table is less than 25 mm. Tacking bolts are designed to clamp 25 mm thick Fireball blocks + 25 mm thick tables. Thinner tables will require a spacer for the tacking bolts to work properly.
For Dragon Wagon series tables, the tables are 12.7 mm thick, so we recommended use of a 1/2" (12.7 mm) thick spacers on each tacking bolt.
If you have a table that is 16 mm thick recommend the 3/8" (9.5 mm) thick spacer.
If you have a table that is 19 mm thick recommend the 1/4" (6.35 mm) thick spacer.
Multiple spacers can be used together. Spacers contain an internal o-ring to keep them them in place when mounted on tacking bolts.