Sonnax super hold servo kit 28821-09K is an all-in-one upgrade ideal for a competitive edge in GM Powerglide applications where racers are looking to reduce line pressure to free up horsepower. The kit's dual piston design features 30% more apply area to increase band apply force at your current line pressure or allow you to reduce line pressure by 20% to 30% while maintaining the same apply force.

• Dual piston design for 30% more apply area
• Spring counteracts pin bias effect up to 275 psi
• Improved sealing throughout
• Low-profile design ensure adequate clearance
• 6061 Anodized billet aluminum cover