Duo Memory cards (TenNoKoe Banks)

Is the card based on a battery? I would assume not because it doesn't look thick enough to have one. I already have one, and I picked up two more for $15 each, do you guys think I got ripped off or what?

BTW: This board has been a bit slow lately

Edit: another question, were there any cards that allowed direct save?
Where did you find these memory cards, I am intrested in finding them, since I am going to get a Turbo Duo soon?
playthegames.com has kisado converters listed for $79 (preorder) but well, their reputation isn't that great. I don't have a converter, I have a japanese duo.
good show, ten no koe bank is an awesome card and is pretty tough to find. Allways get one if you can....and DO not buy from play the games....they are assholes and they rip people off....they also have no respect for anyone at all and its hard as hell to even get the jerks to email you back!! Do not go for play the games. Lik Sang all the way for allmost any nice items....if myou need a converter for the duo do NOT get the kisado converter they are the worst ones ever produced, I bought 3 of them and none of them work good with the arcade card!! Waste of money!! Kisado=Crap !!
Should I also avoid the Play the Games auctions on E-bay too, or are they jerks all around on their auctions and their site?
yikes....they sell stuff on eBay also....good god....I wouldnt go there dude.
I have personally tried to contact them leaving emails and messages on thier answering machine, and never get a reply.....they suck!! and they are here in the states.....hell I got way better responce from Lik Sang and they are in Hong Kong! go figure....
I've been playing around with this tennokoe bank that I have... does this thing have an option to delete saves? I have tons of saves on it and I want them gone.
I don't know if you can delete the save files per se but you can save over the existing sava data if you want. Either that or just transfer no save files from your system's memory and it should delete the saves files on the Tennokoe Bank.