I have a friend who uses 51 duo (not at all familiar with this, but they look like Vapor4Life Kr808's. Is anyone familiar with these and would they be interchangable? She has only had her batts about one month and already they are dying...I'm still vaping with my original KR808 from last march!! Any suggestions?
TheBlueAdept is correct, the 51 duo is KR808d-2, while Vapor4Life batteries (not including the OMG mod) are KR808d-1. If your friend wants to make a transition to the more popular d-1's (including Vapor4Lifes) and has an investment in d-2 supplies, an adaptor can be used. There is one for d-1 carto to d-2 battery and there is one for d-2 carto to d-1 battery in the following link. I used them over a year ago and they worked for me. LeCig Electronic CIgarette Store - Adapters