4-Pack Danly Die Springs. 

SPRG.1.250X4.50-RED-HVY-DUTY

Wire Type: Rectangular

A - Hole Diameter: 1 1/4(in) 32(mm)
C - Free Length: 4.50(in) 115(mm)

Spring Constant: 60.70(lbs per 1/10in) 106.0(N/mm)