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I have some similar to these but designed for 6AA to 2D for $38 plus $6 shipping to 50 States.I'm looking for a 6AA to 2D adapter
I wasn't sure of that due to the 2xD part, putting the cells in series would increase the voltage and depending on what OP wants to put them in it could go bztch instead and fry if too high a voltage is applied.I think the OP wants six AA batteries in series, as opposed to the 3 parallel x2 configuration of the D adapters.