This is a spring tester for testing the spring rate of small springs. This design allows for creating fixture blocks to hold the string in the upper and lower jaw blocks so that testing springs in assemblies or separately is possible. I have included fixture models for Daisy old and new style poppets. You'll need to thread the indicator clamp holes 4mm and install screws to clamp the indicator in the jaws. You'll also need a postage scale and some sort of press. To preform the test simply assemble the tester, insert the spring to be measured and place the tester on the scale in the press. Zero the scale with the tester on the scale. Place the top of the tester just touching the top of the spring. Zero the indicator. Slowly lower the press to compress the spring being careful not to fully compress the spring. Read the distance traveled and weight on the scale. Divide the weight on the scale by the distance traveled to get the rate of the spring.