Short answer. Begin with the material of the window or door frame, then compare the receiver and intended compression gap against the aluminium Q-LON catalogue—not just against a familiar-looking bulb. Schlegel has a dedicated aluminium windows-and-doors table divided into Type A, B and C groups. source A catalogue match is a candidate for verification, not a promise that a replacement will stay retained or seal correctly.
Read the aluminium table without turning it into a fit guarantee
Start a measurement record with three separate fields: the aluminium system or frame identification; the shape and depth of its undamaged receiver; and the closed-position clearance that the gasket must accommodate. Schlegel’s Q-LON aluminium table (printed pp. 14–15) divides listed profiles into Types A, B and C; the group name by itself does not specify your receiving channel.
Six-field identification worksheet
| Record before choosing | What to enter | Decision this supports |
|---|---|---|
| Actual assembly | Aluminium confirmed, unknown, or other | Use the appropriate material-specific table |
| Receiver photo | Close-up looking into clean, intact retaining groove; mark which edge is the sash | Compare retention shape, not colour |
| Physical groove dimensions | Throat width and accessible depth, with units and measurement uncertainty | Check against the exact catalogue row |
| Closing gap | How and where the observed mating-surface gap was obtained | Identify whether a manufacturer's gap field is relevant |
| Existing seal evidence | Profile, insert, marking and side-on photo, if available | Avoid guessing from an empty slot |
| Product/system record | Window system and evidence of original part, if known | Resolve compatibility outside the generic table |
Choose a result: (A) Receiver geometry, seal position and official system specification all agree: keep that evidence with the part number for an installer to confirm. (B) Only catalogue dimensions look similar: label it candidate only; request a matched system/profile check before buying. (C) Groove is obscured, damaged or frame material unknown: do not trim, enlarge or press a new seal into place on this evidence.
Material is another label, not a fitting shortcut
Schlegel describes Q-LON as a polyurethane foam core enclosed by a weather-resistant polyethylene film. source That construction description does not identify an installed part number. Two photographs—one of the undisturbed groove, one of the meeting surfaces—usually communicate the uncertainty more clearly than a brand name alone.
Official sources and precise sections
- Schlegel Q-LON high-performance sealing solutions / no printed revision stated,
PDF index 7 / printed p14–15; aluminium table Type A/B/C— https://www.schlegel.com/wp-content/uploads/2026/07/Schlegel-QLON-snipped_compressed.pdf - Schlegel Q-LON high-performance sealing solutions / no printed revision stated,
PDF index 7 / printed p14–15; group headers— https://www.schlegel.com/wp-content/uploads/2026/07/Schlegel-QLON-snipped_compressed.pdf - Schlegel Q-LON high-performance sealing solutions / no printed revision stated,
PDF index 4 / printed p8; Materials and Colours— https://www.schlegel.com/wp-content/uploads/2026/07/Schlegel-QLON-snipped_compressed.pdf
Next, select a candidate profile code from the correct Type A/B/C column and copy its full manufacturer drawing dimensions—including retention foot or base and compressible sealing body—beside your measured cross-section. If any receiver dimension or attachment style differs, keep the profile unconfirmed rather than trimming the channel.
For a parts inquiry, send the exact Schlegel profile code, the original catalogue page, receiver photographs, frame-system identity and clearance measurements to the manufacturer or system supplier. Even a close dimension match is only a candidate until the installed window or door system and fitting conditions are confirmed.