[THOR450]

go to google images and look at clam shell spring compressors etc and see if that helps looking at different but similar images...

 

[THOR450]

Im guessing you already had the coils removed and replaced by a shop? If you still need to use a compressor, did you try the "loaner" ones at your local auto parts shop? That one you have may only be suitable for the smaller diameter coil springs in passenger cars????