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 90-3400-265 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 90-3400-265 from standard bulb seals is its fin design. Two lateral fins extend outward from the bulb body on each side, preventing the bulb from flopping or rolling sideways under compression while simultaneously expanding the total contact surface against the RV body wall. The 15 ft length is the smallest pre-cut option in this series and is ideal for single-side replacement, top seal upgrade only, or profile verification before committing to a longer full-perimeter purchase. 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 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
Excellent upgrade over existing slide-out weatherstripping — use for top seal only or full single-side replacement without touching the rest of the system
The 90-3400-265 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) Top Seal Upgrade: This seal can be used to upgrade just the top seal of an existing slide-out without replacing the full perimeter system — the 15 ft length is particularly practical for this application, as most single slide-out top runs fall within the 10–15 ft range. Profile Verification: The 15 ft strip is also a cost-effective way to verify that the C-channel fits your specific wiper seal track before purchasing a longer 30 ft or 60 ft roll for a full perimeter replacement. 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 profile • Confirm your run length: A 15 ft strip covers one side of a standard single slide-out or a typical top seal run — measure the run before ordering to confirm this length is sufficient • 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 the run 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 the run and cut the new bulb seal strip to the required length using a sharp utility knife 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 run 6. Seat Fully: Confirm the C-channel is fully engaged on the track along the entire length with no sections lifting or partially seated 7. Inspect End Joints: If installing alongside an existing strip on adjacent sides, ensure the abutting ends meet cleanly with no gap 8. Retract and Test: Retract the slide-out fully and inspect the contact line between the bulb seal and the RV wall — fins should compress evenly with no gaps or rolled sections 9. Check Corners: Confirm corner transitions are snug where this strip meets any adjoining seal run
In The Package: • One (1) continuous 15 ft strip of 90-3400-265 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 • 90-3401-265 — Same Profile, 30 Ft • 90-3402-265 — Same Profile, 60 Ft (full perimeter) Recommended Tools (Not Included): • Sharp utility knife for cutting seal to length • Tape measure for measuring the slide-out run • 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: For replacing a short damaged section or spot-checking C-channel fit before any further purchase 15 Ft Strip (This Item): Covers one side of a standard single slide-out or a full top seal run. The most practical option for a top-seal-only upgrade or single-side replacement — and a cost-effective way to verify fit before ordering a longer roll 30 Ft Strip (90-3401-265): Covers two to three sides of a standard single slide-out. Good for partial perimeter replacement or when the top and one side need replacing together 60 Ft Strip (90-3402-265): Full-perimeter coverage for large single slide-outs or two sides of a dual slide-out. Minimizes field joints for the most consistent seal Tip: Measure the run you intend to replace and add 10% for cutting allowance. If you’re upgrading only the top seal, the 15 ft strip is almost always sufficient for a standard single slide-out top run.
The fin design directly addresses the two most common failure modes of round bulb seals: side-flop under compression and insufficient contact surface against the coach wall. At 15 ft, this strip is the right starting point for a top seal upgrade or a single-side replacement — and if the fit is confirmed, the same profile is available in 30 ft and 60 ft lengths for full perimeter coverage.