The integral mechanical drilling jar type "JSZ" is a double-acting mechanical drilling jar. The down hole jarring blow is not adjustable in the down hole (only can be adjusted in the pipe yard ). It is the shortest drilling jar, and can self-lock in drilling operation. Type JSZ46 JSZ62 JSZ64 JSZ80 Slip Mandrel VS Mandrel 3~15 Piston VS Slip Mandrel 3~10 Connection of Outer Barrel 9~42