I was ordering Sandisk 200GB that should give me plenty of channels. Just kidding was hunting a 4 GB ,doesn't it need to be as high of speed you can get or really makes no difference .I have a 2 GB but it is around 5 or 6 years old .I have a 64GB U1 which would be fast enough but over kill on the size ,I heard it will recognize a 64 GB.