Camshaft mount shim set for Datsun 240Z, 260Z, 280Z and 280ZX, 1970-1983. These shims are .015" thickness. Cam tower shims are needed if you mill the cylinder head surface a significant amount so that the timing chain has too much slack in it and the camshaft needs to be raised. These shims fit under the camshaft mounts. .015" thick.