EPDM rubber slide-out bulb seal with rigid C-channel and anti-flop fins. Slides onto the wiper seal track to seal against the RV body when the slide-out is closed. Fins prevent side-flop under compression and increase the sealing contact surface. An excellent upgrade to existing slide-out weatherstripping — seen on many new RV trailers from the factory. Hand crafted and made in USA.
The Steele Rubber Products 90-3401-265 is a 1-1/8" high by 1-9/16" wide EPDM rubber bulb seal with fins, featuring a rigid “C Channel” section that slides onto the track located on the wiper seal. Like other C-channel bulb seals in the Steele Rubber lineup, the channel grip eliminates the need for adhesive — the seal locks onto the wiper seal track and holds its position through the full range of slide-out extension and retraction cycles. When the slide-out is retracted and closed against the RV body, the bulb compresses to form a weathertight seal that blocks rain, wind, road debris, and pests from entering the gap between the slide-out and the main coach wall.
What distinguishes the 90-3401-265 from standard bulb seals is its fin design. Two lateral fins extend outward from the bulb body on each side. These fins serve two simultaneous functions: they prevent the bulb from flopping or rolling to one side under compression — a common failure mode on standard round bulb seals that creates an uneven seal — and they expand the total contact surface between the seal and the RV body wall significantly beyond what a plain round bulb provides. The 30 ft length is well-suited for replacing two to three sides of a standard single slide-out or for upgrade jobs where the full 60 ft perimeter roll is more than the project requires. Available by the foot and in 15 ft, 30 ft, and 60 ft pre-cut lengths.
Slides directly onto the wiper seal track — no adhesive or fasteners required; locks in position through the full slide-out extension and retraction cycle
Lateral fins prevent the bulb from rolling or flopping sideways under compression, ensuring consistent, even sealing contact across the full slide-out perimeter
Fins increase the total sealing surface against the RV body wall beyond what a plain round bulb provides — a more complete seal against weather, water, and pests
An excellent upgrade over existing slide-out weatherstripping — can be used to upgrade just the top seal of a slide-out for added weatherproofing without replacing the full system
The 90-3401-265 Bulb Seal With Fins is designed for RV slide-out systems that use a wiper seal with a built-in track channel. The C-channel section of the bulb seal slides onto this track, allowing the wiper seal and bulb seal to work together as a complete slide-out perimeter sealing system. Compatible Wiper Seal & Track Part Numbers: This bulb seal is designed to work primarily with the following Steele Rubber wiper and track parts (sold separately): • 70-3884-265 — Small Wiper with Track • 70-3883-265 — Medium Wiper with Track • 70-3835-265 — Large Wiper with Track • 70-4120-265 — Track Channel (for additional sealing configurations) Upgrade Application — Top Seal Only: This seal can also be used to upgrade just the top seal of an existing slide-out without replacing the full perimeter system. Upgrading the top seal adds a more complete weatherproofing layer on the surface most exposed to rain and wind-driven water. New Trailer Fitment: This bulb seal with fins is seen on many new RV trailers as original equipment, making it the appropriate replacement for RVs that left the factory with this fin-style bulb profile. No specific RV model or brand fitment list is available for this part. Always verify that your wiper seal track accepts the C-channel section of this bulb seal before ordering. Measure the existing bulb seal height (1-1/8") and width (1-9/16" at fins) to confirm the correct profile.
The C-channel section of this bulb seal must match the track on your existing wiper seal. An incorrect channel size will result in a loose fit that allows the seal to pull off during slide-out operation, or a channel too tight to slide onto the track at all. • Identify your existing wiper seal: Locate the wiper seal on the slide-out frame. If it has a track channel, confirm its dimensions match the C-channel on this bulb seal • Measure the existing bulb seal: If replacing an existing fin-style bulb seal, measure its height (1-1/8") and full fin width (1-9/16") to confirm this is the correct replacement • Confirm slide-out perimeter length: A 30 ft strip covers approximately two to three sides of a standard single slide-out — measure the full perimeter before ordering to confirm the correct length • No adhesive is used: Installation requires sliding the C-channel onto the wiper seal track — no surface preparation or adhesive application needed
Step-by-Step Installation: 1. Extend the Slide-Out: Fully extend the slide-out to provide clear access to the wiper seal and its track channel on the slide-out frame 2. Remove Old Bulb Seal: Slide the existing bulb seal off the wiper seal track, working from one end along the full length of each side 3. Inspect the Wiper Seal Track: Check the track channel for damage, debris, or deformation. Clean if needed before installing the new seal 4. Cut to Length: Measure each side of the slide-out perimeter and cut the new bulb seal strip to the required lengths 5. Slide C-Channel Onto Track: Starting at one end, align the rigid C-channel of the new bulb seal with the wiper seal track and slide it into position, working steadily along the full length 6. Seat Fully: Confirm the C-channel is fully engaged on the track along the entire run with no sections lifting or partially seated 7. Repeat for Each Side: Complete the same process on all applicable sides of the slide-out perimeter 8. Retract and Test: Retract the slide-out fully and inspect the contact line between the bulb seal and the RV wall — the fins should compress evenly with no gaps or rolled sections 9. Inspect Corners: Check that corner transitions are snug with no gaps where adjoining strip ends meet
In The Package: • One (1) continuous 30 ft strip of 90-3401-265 EPDM Bulb Seal With Fins and Rigid C-Channel Recommended Companion Parts (Sold Separately): • 70-3884-265 — Small Wiper Seal With Track • 70-3883-265 — Medium Wiper Seal With Track • 70-3835-265 — Large Wiper Seal With Track • 70-4120-265 — Track Channel • 90-3402-265 — Same Profile, 60 Ft (for full perimeter replacement) Recommended Tools (Not Included): • Sharp utility knife for cutting seal to length • Tape measure for measuring slide-out perimeter lengths • Flat blunt tool for seating the C-channel onto the track in tight sections
This bulb seal is available in four purchasing options to match the job size: By the Foot: Ideal for replacing a single damaged section or verifying C-channel fit on your wiper seal track before committing to a longer purchase 15 Ft Strip: Covers one side of a standard single slide-out, or one longer run such as the top seal. Best for single-side replacement or top seal upgrade only 30 Ft Strip (This Item): Covers two to three sides of a standard single slide-out. The practical mid-range option for partial perimeter replacement or upgrade jobs that don’t require the full 60 ft roll 60 Ft Strip (90-3402-265): Full-perimeter coverage for large single slide-outs or complete replacement of two sides of a dual slide-out. Minimizes field joints for a more consistent seal Tip: Measure all sides of the slide-out perimeter you plan to replace and add 10% for cutting allowance before selecting your length. A continuous strip with fewer joints provides a more consistent seal than multiple short sections butted together.
The fin design is not a cosmetic difference — it directly addresses the two most common failure modes of round bulb seals: side-flop under compression and insufficient contact surface against the coach wall. RV manufacturers have adopted fin-style bulb seals as original equipment on new trailers precisely because they provide a more consistent and complete seal over the life of the slide-out system.