Firewall Wire Boot – Universal Cable Pass-Through Seal

Description

Route wiring, air lines, or sensor hoses through a metal firewall or bulkhead without leaks or abrasion. The Daystar KU20040BK Firewall Wire Boot provides a clean, protected pass-through for 3/8″ to 1″ bundles. Drill a 1.25″ pilot hole, seat the boot, trim to fit, and cinch with a zip tie. Made in the USA.

Key Features

• Universal Fit: Accommodates wire/tube bundles from 3/8″–1″
• Leak-Resistant Seal: Helps block air/water intrusion through firewall penetrations
• Edge Protection: Shields insulation from sharp metal to reduce chafing and shorts
• Fast Install: 1.25″ hole, trim-to-fit opening, secure with zip tie
• Durable Construction: Heat-resistant, automotive-grade elastomer; Made in USA

Perfect For

• Truck accessories, lighting, and upfitting
• DIY Box truck, overland vehicle conversions and pass-throughs
• Car audio power/ground, DSP, and sensor wiring
• Air systems (on-board air, lockers) and auxiliary plumbing

Specifications

Brand	Daystar
Part #	KU20040BK (Single)
Fit Range	3/8″ – 1″ wire/tube bundles
Pilot Hole	1.25″ (32 mm) in firewall/bulkhead
Closure	Trim-to-fit opening + zip tie
Material	Automotive-grade elastomer (heat-resistant)
Country	USA

Installation Overview

1. Plan the routing. Verify clearance on both sides of the firewall and avoid OEM harnesses/lines.
2. Drill a 1.25″ hole; deburr edges.
3. Press the boot into the hole until fully seated.
4. Pass your wiring/hoses through the slit; trim the opening to match bundle diameter (3/8″–1″).
5. Cinch the neck with a zip tie for a tight seal. Test for chafe-free clearance and leaks.

What’s In the Box

• (1) Daystar Firewall Wire Boot – KU20040BK
• (1) Zip tie

Single vs. 5-Pack

Need to outfit multiple pass-throughs? Choose the KU20041BK (5-Pack) for shops or complex builds. Same sizing/installation—better unit cost per boot.

FAQs

Will it work for hoses?

Yes—within the 3/8″–1″ range. Ensure the hose OD matches and trim the opening for a snug seal.

What if I already have a factory hole?

If the existing hole is near 1.25″ and the sheet metal is sound, you can deburr and install the boot there.

Heat exposure?

The boot is heat-resistant for typical engine-bay duty. Avoid direct contact with exhaust components.