I ordered 2.1 x 5.5mm. The seller sent me 2.5x5.5mm. Now they say 2.1 = 2.5 and supposedly it's the same thing. Well i don't believe that. To me it's 0.4mm difference meaning bad fit. So not happy with the advertising, selling products they don't have, nor the aftersale service. (on the last photo the last barrell on the right is 2.1 ID ... if i can see the difference, it's not the same)