Polarity of jack plug on Ultrafire bike lamp

[Whitedwarf]

I bought one of those high lumen ultrafire bike lights from dx minus power supply (because I'm loath to use their brand x cells). It came with a jack plug to fit the 8.4v 18650 battery packs deal extreme sell; am I correct in thinking the tip on the plug would be connected to positive and the barrel on the outside negative?

 

[DavidAD]

Yes. Sometimes the plugs are slightly different at the outer sleeve.