Proven Reliability: With a rich history of excellence, Sealey tools are trusted by professionals worldwide. Size: 6mm Pipe x 1/4"BSP thread. Thread: 1/4"BSP. 1 2 3 4 5 6 7 8 9 10 11 12. Key Points. One of a comprehensive range of high quality components for the John Guest Speedfit® Pneumatic Coupling System.