A polymethylene polyphenylisocyanate that contains MDI. This product’s viscosity and functionality have been optimized by maintaining a high diphenylmethane diisocyanate content and a high percentage of ortho-para isomers to provide excellent flowability and fast curing in a variety of polyurethane applications. This unique combination makes this product suitable for a full range of low and high density semi-flexible and semi-rigid foam applications that demand fast demold times for intricate parts.