How it works
The mesh is permanently pleated, like a paper fan, and threaded with cords that run through guides at the head and sill. Pulling the leading edge across the opening unfolds the pleats; pushing it back stacks them into a slim channel at the side.
There is no roller and no spring. The pleats hold their own shape and the cords keep them aligned, which means one fewer mechanism to fail — a genuine advantage over a spring-loaded roller screen in a humid, salty climate.
Where it is the right answer
Outward-opening sashes
This is the main case. A casement or top-hung window swings outward, so any screen has to sit on the inside — and it cannot occupy the space the handle sweeps through or the sash needs to open.
A pleated screen folds sideways into a narrow channel, clear of both. A framed sliding panel would sit permanently across part of the opening; a pull-down screen can conflict with a top-hung sash.
Wide openings
A single pleated run spans considerably wider than a framed panel can sensibly manage, because the weight stays low and stacks at one end rather than hanging from a track.
Where the screen should disappear
Retracted, a pleated screen is a strip a few centimetres deep at the edge of the reveal. If the view matters and the screen is only needed in the evenings, this is the neatest result available.
Trade-offs, honestly
Less robust than a framed panel. It is a folding mesh, not a rigid sash. On a door used many times a day, especially with children or pets pushing at it, a sliding mesh will last longer.
The bottom guide needs to stay clean. Grit in the lower guide is what makes pleats fold unevenly. In Mumbai that means wiping it out periodically rather than occasionally.
More expensive than a basic framed screen. Not dramatically, but it is a more engineered product.
Configurations
Single-opening, where the mesh stacks at one side, or centre-opening, where two halves meet in the middle and stack at both jambs. Centre-opening halves the distance the mesh has to travel and is worth it on very wide runs.
For spans beyond what a standard pleated system handles, zig-zag mesh is the heavier-duty version of the same principle.
Cleaning
Extend it fully, brush or vacuum gently along the pleats, then wipe the head and sill guides. Doing this a few times a year keeps the fold even and the airflow up — see the insect screen range for how dust affects every screen type in this city.