Power socket size for MAX BR1 MK2?

Could someone please confirm the size of the power socket on a MAX BR1 MK2. I’m think it’s 2.5 mm but 2.1 looks pretty similar so it’s not obvious. I’m ordering a custom cable for my RV and I couldn’t find it in the specs.

Thanks

In case someone else needs this, it looks like it’s 2.1 mm so I guessed wrong. I bought a 2.1 cable plus a 2.5 adapter but the 2.1 seems to fit well.