Raven cylinder, Raven tapered cylinder head, Raven piston and Raven spring guide in one convenient set. This particular assembly is for the Tokyo Marui VSR-10 spring bolt action rifle.
Raven (PDI) is a top premium line of products; if you are modifying your weapon for top performance, Raven is a good choice. Besides being smooth, reliable and robust the tapered head also smooths out the air flow which improves shot-to-shot consistency even further than an already well sealed setup.