DRBGBFSL-PTE exit button, flush mount architrave 2mm stainless steel facia with large green dome exit button
IP66 rated for external use
Architrave flush mount
Changeover contacts (C/NO/NC)

Size: 85h x 39w x 2d mm
Optional flush mount bracket is approximately 30d mm

Face plate: 2mm Stainless steel face plate engraved Press To Exit
Exit button: Large 35mm green dome exit button (Protrudes approximately 23mm)
Contacts: Normally Open & Normally Closed contacts
Tested for: 1,000,000 operations
Rating: IP66 rated for external or indeed internal use

Why is a flush mount bracket not supplied?
If you are replacing an existing flush mount exit button, then it is more than likely to have a back fitted already, likewise with fitting in to a hollow steel post, then you would use self tapping screws for this - the flush mount bracket wouldn't usually be required

As per the above image and 2 x fixing screws