Prevent pressure drops in high RPM GM TH400 and Powerglide racing applications with this new, specially calibrated high RPM checkball capsule from Sonnax. Testing has shown that OEM checkballs in listed racing applications are unreliable above 5,500 rpm. At higher speeds the checkballs can unseat, resulting in drop of line pressure or converter pressure. There are many variables that effect check ball performance including diameter of ball, mass of ball, distance from centerline, seat angle, oil pressure and RPM. To overcome these issues, Sonnax developed a unique capsule that is specially calibrated to prevent drops and keep racing applications that see above 5,500 RPM running at peak performance. Easily replace the checkball in the piston or drum with this universal capsule that can be installed in existing TH400 pistons or drums and Powerglide drums. Visit www.sonnax.com to learn more about preventing pressure drops with Sonnax High RPM Checkball Capsule 57510-01. Ask for this and other Sonnax transmission parts from performance parts distributors.