I installed these on my Ender 3 Pro 3D printer to replace the stock springs. Noticeable, immediate improvement. I just wish they would sell them in packs of 4 for less as I won't be using the rest.
Pros
Compression Spring Size: Orifice (OD): 0.31"/8mm Shaft Diameter (ID): 0.16"/4mm; Length: 0.78"/20mm, correct size to use