In reply to Davy Murphy:
There is a chart to compare here:
https://cdn.shopify.com/s/files/1/1554/2851/files/cam_size_comp_chart2.1.jp...
According to this though, the grey Friend is size 4 not 5 though? In which case it is equivalent to a grey dragon 6. The colours are pretty consistent between most brands.
Edit: this is also useful, and gives lots more than the rock+run chart:
https://camparator.com/compare/cam/selection/?i747=1&i748=1&i379=1&...
So if you do indeed have the size 5 friend, supposedly red, it would be equivalent to the purple size 7 Dragon
Post edited at 12:22