Jack,
The oval plate has a “turn down” around its edge and is secured with four small slotted screws – holes visible in picture.
The flap is hinged to the boot lid and when the boot is open is secured “up” to a plate on the boot with a small turnbuckle fitting.
When the flap is down it rests on the boot floor – it does not go into the “storage” bin. It is made of metal.
Not sure what you mean concerning the D strips? The flap has metal strips on the underside to reinforce the flap?
Let me know if you require further info/clarification.
Alistair
Alistair