A plug for displacing cement in a downhole environment comprising a seal surface having at least one profile. The seal surface, in response to applied pressure, creates a hydraulic seal with another device. The seal surface can be made of molded rubber and the profile formed thereon can be formed from the molded rubber and during the molding process. The profile can be a semicircular profile or multiple semicircular profiles. The profile or profiles can be one or more semicircular profiles and one or more line profiles. The plug can be a bottom plug and the seal surface can be an upstream seal surface and the other device can be a float collar. The plug can be a top plug and the seal surface can an upstream seal surface and the other device can be a bottom plug.