Anyone that builds engines has probably had to do a valve spring swap in the vehicle. It’s not pretty at best and a full-on disaster if you lose a retainer lock in the engine while struggling to hold a lever arm compressor in one hand and removing retainer locks with the other. This tool allows a single technician to replace valve springs in a safe and professional manner without removing the cylinder heads from the vehicle. By incorporating a modified follower bucket to compress each spring, the retainer locks can be set on top of the follower and moved safely into place with no chance of falling in the engine, leaving both hand free to precisely complete the job. It can also be used with heads off the engine. Worth every penny at $89.95 even if you only use it once! Fits most Nissan VQ, KA, QR, & VK Engines. We also loan these tools at no charge to customers purchasing JWT Cam and Spring Sets.