This is a Novarossi 41015 Short Conical On Road Manifold. This short 5-ring manifold is recommended for .21 class on road engines, and tracks that require top end power delivery. Package includes two gaskets, one long spring and three short coupler springs.
Conical vs. Non-Conical:
Conical manifolds have a tapered inner diameter that gradually increases throughout the length of the manifold and will produce more power than a standard manifold at the expense of decreased runtime. Non-Conical (or standard) manifolds have a consistent inner diameter throughout the entire length of the manifold and will provide smoother power delivery and better runtime than a conical manifold.