Most modern uPVC windows installed by Barratt, Persimmon, Bellway, Taylor Wimpey, Avant, CALA, Ogilvie, and Robertson Homes feature rubber glazing bead depths between 18mm, 20mm, 24mm, or 30mm. Measure the distance from the glass surface to the front edge of the uPVC bead frame. Perfect Fit bracket clips are available in matching depth sizes (18mm to 30mm) for a flush, factory-fitted appearance.