These heavy duty intake boots are Four Ply Silicone and won't crack or split like the factory rubber boots. Features: Heavy Duty High Temperature Four Ply Silicone Boots, Every boot/hose that Sinister manufactures is designed to exceed factory specifications, Won't split or crack like the factory rubber boots can, Increased airflow, quicker turbo spool, and lower EGT's, Kit Includes - (4) Four Ply Silicone boots and (8) Stainless Steel Spring Clamps, 300 Series Stainless Steel Spring Clamps., Burst rating of 400psi!!