These sets consist of high temperature heat resistant, silicone gray dust boots and high temperature pressure seals, manufactured by Frenkit Performance for most late-model Brembo calipers. These are the perfect components for street and track-oriented performance vehicles!
 
These are silicon dust boots and high temperature pressure seals and are recommended for track/racing/high performance driving events.
 
Included are the following components:
36mm (36 mm) High Temp Gray Silicone Dust Boot, Part Number 750.99003, Quantity 2
36mm (36 mm) Pressure Seal, Part Number 753.99003, Quantity 2
40mm (40 mm) High Temp Gray Silicone Dust Boot, Part Number 750.99005, Quantity 2
40mm (40 mm) Pressure Seal, Part Number 753.99005, Quantity 2
 
This is also StopTech kit part numbers:
143.99036K - 36mm
143.99040K - 40mm
This seal kit replaces OE Brembo Dust Boot part numbers:
20.4872.44 (20 4872 44) - 36mm
20.4872.46 (20 4872 46) - 40mm
This seal kit replaces OE Brembo Pressure Seal part numbers:
05.5955.56 (05 5955 56) - 36mm
05.5955.58 (05 5955 58) - 40mm
This seal kit replaces OE Brembo Rebuild Kit part numbers:
105.5955.56 (105 5955 56) - 36mm
105.5955.58 (105 5955 58) - 40mm
 
Typically on a 4-Piston caliper, there are two of each piston size, so this combination should service one front caliper (4 pistons total).  These are not application specific, rather for those who may have a single torn dust boot or failed pressure seal or for those who are rebuilding their calipers; however, this kit will may work for many aftermarket Brembo or StopTech 4-piston caliper combinations.