Material : Chrome steel , triple plated Copper / Nickel / Chrome 

Springs : Comes with 2 sets of throttle springs, 1 set of lighter and 1 set of heavier tension so you can adjust the pedal fell

Hardware :Comes with all the hardware necessary to mount to your carb

Application : Fits Holley 2300 / 4150 / 4160 series carburetors

Will not fit 4500 series dominator carburetors

Will not fit Demon or Edelbrock carburetors (Without light mods)

Drag strip : Compliant with most drag strips rules for dual throttle springs requirement

Attributes: Provides smoother throttle operation than most other dual spring assembles. Mounts to the carburetor not the manifold which makes for a cleaner setup

Installation :Thought it looks complicated at first it is relatively easy to put together on your Holley we  send a photo of the assemble to aid you in installation (carburetor shown not included)