JSB 18.13 grain pellets are manufactured in Bohumin, Czech Republic by Joseph Schulz, are considered by many to be the most accurate pellets available in the entire world. The Exact Diabolo is an intermediate weight, round nose pellet that will deliver improved flight stabilization and fine accuracy. Ammunition for seriously powerful air guns. Have you really got a powerful weapon? Then Exact Heavy is the right choice! They are heavy, stable and accurate.