The sheet metal adjustment wrench supplied with my 0.0005”/foot machinist level never worked very well for making level calibration adjustments. The level is well built but the adjustment spanner wrench made from thin metal could be improved. I made two types of spanner wrenches from 0.125” dia. 303 stainless steel and 12L14 steel rods. Using the two wrenches together simplifies the process of loosening one adjustment nut while tightening the opposing adjustment nut. The round adjustment nuts have a series of 0.080” dia. sprocket holes evenly spaced around the perimeter. The spanner wrenches are quite small in order to fit into the small access hole on the side of the level. The ID and OD of each spanner wrench is only 0.400” and 0.560” respectively, the handles are 2” long, and the spanner pin diameter is 0.080”. I used a gage pin to determine the best fit diameter for the spanner pins. Spanner wrenches work very well and I can quickly adjust the zero position of the level.