This spark tester is well made for the price. It is easy to adjust and the recessed block makes it easy to see the spark. The spike that goes into the plug socket is loose so you have to put pressure on the clamp to hold it in place. The biggest problem is that the spike that goes into the plug socket is not fastened to the body of the tester. It just falls out. The fix for this is a small amount of 5 minute epoxy where it goes into the body of the tester. It is then a useable product.