Easy to use. I used the template to increase the instrument hole from 2 inch to 3-1/8 without issue on experimental aircraft.

Template was easy to use, drawback is the .177 drill guide holes are larger than 6/32 screw size forcing you to drill oversize 8/32 for some instruments. With The center screw tightened you can still move the template on thinner panels so you need to be careful not to move anything. Extending the arms of the clamp bar another 1/8 each side would allow it to clear the 3 1/8 circle template and clamp on thinner panels. A countersunk center screw would allow the panel to still sit flat on the bench while drilling.