Ok, let's address the whole "Peek" B.S.
One of the first question Dunninger encourages students to ask is "What would this look like if a real Mind Reader (a.k.a. Psychic) were to do it?) I'll lay money on it that he/she would NEVER have you write something down and put it into their own wallet, card case or check book, that's what magicians do.
If you think yourself a "Mentalist" you have no need for one of the many different "peek" wallets on the market. That's not the same thing as saying you don't need any wallet, there are several that have been around a good while, that allow you other practical advantages starting with the Mark Striving S.U.C. device (stay away from the knock-off with the note pad). It can be used in a number of ways including peeks but more to my personal taste, as a pocket-desk for Pocket Writing work or when doing Swami work.
Larry Becker's VERSADEX Wallet is one of the best billet indexing systems you could ask for.
I will likewise suggest any wallet that looks like a real man's wallet (hip wallet) that has a Harbin styled switch and if you are into all the card tricks, you may want to make certain it has an easy means of making loads. . . then again, a solid load method is great for billets as well.
I don't know that it's commercially available but there is a wallet with a built-in impression system, I'll have to check on availability with it, it's a bit special and would certainly be one of the more expensive pieces going.
Hope this in-put helps you think things out. . .
