Wehrli 3in x 3.5in ID Straight Reducer x 4in Long Silicone Boot & Clamp Kit

We use these boots specifically when pairing the Square Root Fab intake flange to a Wcfab intercooler pipe.
 
It can be used as a universal boot too if you happen to need something 3" to 3.5". The boot is 4" long. Clamps included!