The 754 consists of a robust, wear-resistant thermoplastic elastomer mechanical seal and is energized by an NBR O-ring. The upper is available in various material options to extend operating conditions. The width of the housing allows the use of narrow pistons.The 754 consists of a robust, wear-resistant thermoplastic elastomer mechanical seal and is energized by an NBR O-ring. The upper is available in various material options to extend operating conditions. The width of the housing allows the use of narrow pistons.