6-Pack Danly Die Springs.
SPRG.0.500X3.00-RED-HVY-DUTY
Wire Type: Rectangular
A - Hole Diameter: 1/2(in) 12.5(mm)
C - Free Length: 3.00(in) 76(mm)
Spring Constant: 7.70(lbs per 1/10in) 13.6(N/mm)