2" to 3" Silicone Reducer Hose 3-Ply Black

Will this work for both coolant and boost applications?

Yes. The 3-ply reinforcement handles positive pressure (turbo/supercharger intake) and negative pressure (coolant overflow return lines) equally well. Just confirm your system's max psi rating before install.

Do I need clamps, and what size?

You'll need hose clamps at both ends — typically 2" clamps on the inlet side and 3" on the outlet side. Check your system's existing clamp size to match; some builders prefer worm-drive clamps for repeated adjustments.

Can I use this straight out of the box or does it need prep?

Straight out of the box is fine. Rinse the inside with clean water before connecting to coolant systems to remove any mold release residue, especially if it's been stored a while.