eh ? the panel look like is was wired in the dark by a trainee...
the pir looks like one screw, there a massive hole in the arse of it, the conductors have been poorly done, the resistors have'nt been cut down or fitted logically
For me It very easy to fit your "scatsecure" sounder, 5 wires, a link wire across the pcb terminals
I could order one today & it should be at yours on Wednesday
However the issue will selling to the public or giving staff kit their not trained & familiar with is the length of time explaining why "xyz" doesn't work & its very rarely anything wrong with the kit