RBS has found with today's race engines that run high valve spring pressure this is a very valuable tool for quick and easy valve spring removal on the workbench. It is designed to work with most any cylinder heads and valve spring combination. It is made from billet alum. with a proprietary wave beam design that offers lightweight with maximum rigidity to offer the racer a strong lightweight tool. The compressor uses dual adjustable ends for perfect and easy adjustment on the spring or valve and the spring side has been hexed so if the racer chooses to use a battery powered impact to speed things up no problem and it has a hand adjusted lock nut to lock the adjuster in place if needed. Spring cage has a 1" I.D. that allows the tool to be used with most all valve springs. The jaw capacity is 8.375" with a throat depth of 5.50 " which is enough for even the hard to fit big cheif and hemi heads. Tool is capable of compressing up to 1000lb. springs with no issues.