What is the exact purpose and benefits of this product? I am currently using acrylic blocks.

I started with acrylic blocks, but sometimes you don't get the full ink coverage or you get a little shadow if you rock your block. With the Misti you can reink your stamp and get perfect coverage. No shadows ever! You can stamp multiple cards, like Christmas cards with perfect placement. The detail on your stamps is amazing. I think this is an awesome product. It is frustration free.

What if u have stamps with wood blocks?

You need to carefully remove the stamp from the block, being sure to keep the foam intact and adhered to the stamp, not the block!! When StampinUp started using the slimmer stamp cases, my demonstrator helped me with this hint: place your block stamps in the microwave for 20-25 seconds, depending on your oven time may vary. Carefully try to peel up one end, I suggest a thin metal spatula to get under the foam, if it buckles or tears, put back in the microwave for increments of 5-10 seconds, again depending on your microwave. The rubber will not melt, and if the foam isn't damaged you should get a perfect stamp every time. I hope this helps!! CJ

I make 5x7 cards is that going to be big enough or do I need the large one

Mary, I make 5 1/2 X 4 1/4 cards and the Mini Misti Stamp Tool is wonderful for me. Even though your cards are somewhat larger, the interior area for stamping should be fine. In terms of having enough surface for creating a lovely design and not having to worry about storage space for a larger implement, I would definitely go for the Mini Misti Stamp Tool.Marnie

what is the largest size paper or card you can use with the mini?

I’m not sure of the exact size of the stamping area. I had initially purchased and immediately returned it as it’s very small; the description lists the mini MISTI as 6"L x 1"W x 4.75"H, but remember that is the outer frame of the entire unit. The stamping area would be much, much smaller. I returned and purchased the regular MISTI.