A stretch ceiling is held in a perimeter (or dividing) aluminium profile. Two common methods: harpoon — rigid harpoon edge seated in the profile groove; and clip — membrane clamped without a separate harpoon edge. Not abstractly “better” — an object, crew, and profile choice.
Harpoon: edge prepared on the membrane; on site it enters the profile. Pros: re-hang and removal often cleaner, tension line more predictable with a correct cut. Many Alumineu series are harpoon-based — including INVISIA shadow gap and CURTINA niches; check SKUs in the catalogue. Cons: cut and edge must be right; on-site trimming is harder than with clip.
Clip: membrane is clamped in the profile. Pros: on-site adjustment, familiar for some crews. Cons: edge quality and re-removal depend on technique; not every architectural node (shadow gap, niche, light) exists in both executions — do not assume 1:1 parity.
Keep terms apart. Harpoon = edge fixing. Shadow gap, curtain niche, light line = jobs. The same job can be harpoon or clip if the series provides it. FLOATIA and CURTINA: pick the job first, then available system and SKU.
In some markets (especially DE DIY) “Keder” is used as a synonym for the harpoon edge — not a separate third fixing method.
Alumineu: EN AW-6063 T5, B2B warehouse Poland. Dimensions and compatibility only from drawing and catalogue.
### FAQ
Swap harpoon profile for clip without a new membrane? Usually no — the edge is system-bound.
What for a shadow gap? First a shadow-gap profile (for example INVISIA class), then check harpoon vs clip availability.
Is “Keder” a third system? In DIY language it usually means the harpoon edge — not a separate mounting system.