MacPherson Strut Spring Hook Compressor These devices quickly and easily compress most sizes of MacPherson strut springs. Setup is fast and simple. Compression is achieved by alternating from one assembly to another. Each device has a heat-treated alloy thrust screw (5/8"�11 x 12") with forged hooks. No. 7294 � MacPherson strut spring hook compressor, for most sizes of MacPherson strut springs.