Phenolic Spacer - BMP Manifold 1/2"The Precision Raceworks Phenolic Spacer is made in the USA from premium fiber impregnated phenolic material. With a Rockwell Hardness of 100 and a conductivity rating of 2. 03 it is the perfect material for insulating between heat generating parts such as the cylinder head and other parts you wish to stay cool like the intake manifold. Our 1 2" phenolic spacer not only provides a thermal insulation between the cylinder head and intake plenum. It has