Downlight hole size.

[happyhacker]

I have bought this Austin downlight from B&Q but some of the instructions are missing & cannot find the make online. I am not sure of the hole size. The distance between the brackets with the spring affair is 86mm. Any one know what hole size and how to fit?

Mayn thanks.

 

[gas man]

regarding cutters had a cheap set from cpc recently all the typical sizes in there probably wont last long but cheap as chips