There is also a smaller version it seems of the BPR-6ES - BCPR-6ES, as I found when I install BPR's on my new engine, and realised the old ones I pulled from the old heads on the engine coming out were smaller socket...
I was sure I had bought BPR-6ES plugs, and upon looking at them, saw they were BCPR6ES.
Looking at the NGK sheet for their product numbers, the only difference between the 2 is the hex size. 20.8mm for the 'B' and 16.0mm for the 'BC' version. Thread size is still the same.
'06 4.2 Supercharged Black/Cream "Jess" -- Bought April 2021 (NZ)
'01 4.6 Vogue Black/Lightstone "Snog" -- Bought Jan 2012
'99 4.6 HSE Cobar Blue/Lightstone -- Sold March 2009
'95 4.6 HSE Epsom Green/Tan -- Traded June 2008