These use a COTS silicone O-ring to seal the tube flange against the head, eliminating the flat gaskets which have been known to leak and cause grief on occasion. Like our SDS valve covers, these billet flanges tighten down flat with even, metal to metal contact so there is no more flange distortion or "give" in the gasket over time. They will come as a kit which also includes the O-rings, silicone hoses and constant tension clamps to replace the factory parts. For carbed engines, we'll supply new standard rubber hoses. Will be available for both 1.5 and 1.75 OD induction tubes, in gold or red anodized finish. I'll try to get a photo of the complete kit this weekend.