[Elecraft] What size DC Power Plug for K1

[JT Croteau]

My K1 did not come with the original DC Power Plug.  I see in the
parts list that J4 is 2.1mm in size.  The local Radio Shack has two
with an ID of 2.1mm - one they call a Size M and the other is a Size
K.

Anyone have a clue as to which would be the better gamble to try so I
don't have to buy both?

Thanks

72 de JT, W6FO