Replacement arrived today.
Tight & secure fit.
Tried in both sides as it isn't handed.
Door is easy as you can hold it in place from the outside whilst closing the sliding window.
There are two 'L' shaped brackets that the sliding window fits into and the design is such that the window latches into a locked position when closed. All pretty tight and very secure.
Kitchen. n/s, window could be done from the inside, I didn't fully latch up the window as it is a tight fit into the 'L' brackets and felt that it would be better with a bit pressure to the outside to complete the latching process.
I only intend to use it in the door.
Construction is rigid and to a very high standard, CNC laser cut frame with inner and outer sections. metal weave mesh in window/vent area, I had the optional fly screen which is a small nylon mesh on the inside trapped between the inner and outer metal layers.
No actual rain protection or channelling nor does it claim to have any. No problem for me as going under the awning.
Much more secure than the large outside fitting vent, which I have already for the kitchen side (these are handed for kitchen or door).
No risk of bending during storage (I tried to straighten the faulty one but even with all my weight on it it wouldn't alter).
The 'L' brackets make it a bit awkward as they stick out about 25mm, See photo.
Frame outer is 27mm x 48mm which isn't too big to find a storage place for it.
Overall I'd recommend it or even a pair. Security is good (more than the glass it's fitted into)
Quality is 10/10.
Appearance is 10/10