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.
 
This kit is specialized for the 2003-2006 Nissan 350Z Track edition or the 2007-2008 Nissan 350Z Nismo edition.  This may also fit some 2003-2004 Infiniti G35 with the factory Brembo brake package.  Please confirm if you are unsure, we're happy to help!
 
Included are the following components:
38mm (38 mm) High Temp Gray Silicone Dust Boot, Part Number 750.99004, Quantity 2
38mm (38 mm) Pressure Seal, Part Number 753.99004, Quantity 2
44mm (44 mm) High Temp Gray Silicone Dust Boot, Part Number 750.99007, Quantity 2
44mm (44 mm) Pressure Seal, Part Number 753.99007, Quantity 2
 
This is also StopTech Rebuild Kit part number:
143.99038K - 38mm
143.99044K - 44mm
This seal kit replaces OE Brembo Dust Boot part numbers:
20.4872.45 (20 4872 45) - 38mm
20.4872.48 (20 4872 48) - 44mm
This seal kit replaces OE Brembo Pressure Seal part numbers:
05.5955.57 (05 5955 57) - 38mm
05.5955.60 (05 5955 60) - 44mm
This seal kit replaces OE Brembo Rebuild Kit part numbers:
105.5955.57 (105 5955 57) - 38mm
105.5955.60 (105 5955 60) - 44mm
 
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.