I like these ones:
http://https://pitstopusa.com/i-23900345-fox-nylon-spring-divider-2-5-spring-short.html
https://pitstopusa.com/i-5077505-hyp...i-d-25-lb.html
They nylon slider is glass filled and the shoulder keeps the helper from fully bottoming out. (it is the short one in the picture) Nylon will not mare up the coilover body like the aluminum ones can. The spring is light enough to compress with one hand while changing springs.