Ok, Ok .... they're drivers and installers for removing the balance shaft bearings and then installing new ones that are solid, meaning they lack an oil hole that's intended to lubricate the front and back balance shafts in their bores. The nuts are welded on 'em so you can use a socket and 1/2" extension to hold 'em so you can pound 'em outta their bores then the seat cut on the tool holds the new bearing on the driver so it can be driven in the bore to then block the oil ports in the block that feed the bearings.

This is done when you remove the front and back counter rotating balance shafts from the bottom end. At about 14lbs of reciprocating mass driven by the crank they consume hp for every revolution of the engine and their only real benefit is to dampen out a transient vibration in the bottom end that occurs between 3k and 3.5k rpm.

Removing the balance shalves removes their parasitic hp drain and then installing new bearings with the oil holes blocked off also gives a healthy increase in oil pressure too, which is what wound up blowin my oil filter off twice, with the second event havin taken out the crank and rod bearings and puttin the old Talon to rest for good.

With right at 200k on the clock, and about 135k of that under my heavy right foot beatin the hell out of it daily, and needin an engine rebuild with the complete suspension needin rebuilt too I scrapped the ol beast and snagged an Eclipse with about 1/2 that many miles on it