The retaining spline must suit the frame groove and mesh. Reusing a brittle or incorrectly sized spline can leave an uneven result. Keep any accessible product information and show the groove where visible, without damaging the frame to obtain a sample.
Measure the existing screen and show how it sits in the opening. Overall dimensions alone may omit clips, recesses or clearance. A customer-supplied replacement should be checked against the fixing arrangement before purchase, especially where the old screen is missing.
Mesh needs suitable tension without distorting the frame. Corners and long sides should be checked during fitting, following the material requirements. Over-tightening is not a way to strengthen an old frame, and loose mesh may reflect a retaining-channel problem.
Fit suitable mesh and spline to an accepted sound frame, or install a compatible ordinary supplied screen and check its fit. Scope limits: Ordinary insect mesh and compatible screen frames only. No security screens, fall-protection claims, specialist glazing or inaccessible high-level work.