Description
Every hole cut in a metal panel is a decision about what will eventually fail. A wire pulled through raw sheet metal will chafe against the edge for a thousand small vibrations, and one day the insulation gives way and the harness shorts against the chassis. The inexpensive answer is a sleeve: a silicone collar that sits in the hole, holds the cable off the metal, and seals the gap against dust and splash without a connector or a gasket.
This is a straight tube sleeve with a 16.5mm inner bore for the wire bundle and a 30mm outer seat for the sheet metal hole, supplied five to a pack. The body is moulded silicone, which stays flexible from deep cold to engine bay heat, resists the oils and solvents that degrade cheap PVC, and does not harden into a brittle ring after a season of thermal cycling. The straight profile is deliberate: it presents a flat seat against the panel so the sleeve cannot be pulled through under cable tension, and it keeps the bundle running perpendicular to the panel instead of kinking at the exit point.
Because the material is silicone rather than rubber, the sleeve can be installed after the harness is already terminated. The wall flexes enough to work the collar into the hole with a blunt tool, then returns to shape and grips. That single property is what makes it useful in repair work, where the alternative is depinning a connector to slide a grommet on from the free end.
The cheapest part in the assembly is usually the one that decides how long the rest of it lasts.
What You Are Actually Buying
✦ 16.5mm inner bore, 30mm panel seat: sized for a wire bundle through a standard sheet metal hole.
✦ Moulded silicone body: flexible from cold to engine bay heat, resistant to oils and solvents.
✦ Does not harden or craze, unlike PVC grommets that go brittle after thermal cycling.
✦ Straight tube profile seats flat against the panel and cannot be pulled through under cable tension.
✦ Installs after the harness is terminated: the wall flexes into the hole and returns to shape.
✦ Seals the panel gap against dust, splash and engine bay grime without a separate gasket.
✦ Five pieces per pack, which covers a full harness run plus spares.
Technical Specifications
- Material Moulded silicone
- Inner bore (wire diameter) 16.5 mm
- Panel hole diameter 30 mm
- Profile Straight tube, flat seating flange
- Quantity 5 pieces per pack
- Temperature behaviour Flexible across automotive cold-start to engine bay heat
- Chemical resistance Oils, greases and common automotive solvents
- Function Wire harness pass-through, edge protection and panel sealing
- Installation Press-fit into the panel hole; can be fitted over a terminated harness
- Colour Black
- Customization Available to specification on request
- Origin Mainland China
Where This Belongs
Automotive electricians use it wherever a harness crosses a bulkhead, a firewall or an inner wing, especially on retrofit work where the loom was built before the hole was drilled. Trailer and caravan builders use it at the point where the lighting cable leaves the chassis. Industrial panel builders use it on enclosure walls to keep cable bundles off a cut edge and to hold a dust seal. Machine shops retrofitting sensors to an existing frame use it because the alternative, depinning a connector to slide a closed grommet on, costs an hour of labour per harness. It is a small part with a narrow job, and it does that job for the whole life of the machine.
Questions Worth Asking
Will it fit my panel hole?
The sleeve seats into a 30mm hole and passes a wire bundle up to 16.5mm in diameter. Measure both the hole and the bundle, not just one: a 30mm hole with a 20mm bundle will leave the cable loose inside the sleeve.
Can I install it without cutting the wires?
Yes. The silicone wall flexes enough to work the collar into the hole from the side, then returns to shape and grips the panel. That is the main reason to choose silicone over a rigid rubber grommet.
How much heat can it take?
Silicone is chosen specifically for engine bay conditions: it stays flexible at cold start temperatures and does not soften or smell at the temperatures a firewall sees. It is not a substitute for a heat shield next to an exhaust manifold.
Does it seal against water?
It seals the gap between the cable and the panel against splash, dust and grime. For immersion or pressurised wash-down, use a proper cable gland with a sealing insert instead.
What is the difference between this and a rubber grommet?
Rubber hardens and crazes with heat and oil exposure, and a closed grommet has to be slid on before the connector is fitted. Silicone stays flexible and this straight-tube design can be installed afterwards.
Are five enough for a full harness?
Five covers a typical full harness run through a firewall plus a couple of spares. Larger builds usually order two packs, since the pass-through points add up faster than expected once accessories are wired.






Customer Reviews
Payment and Security
Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.
