External off the shelf hard drive

Does anyone know offhand an external hard drive already in an enclosure that use's a cable with the eSata male plug so that I dont have to swap out a drive to another enclosure or buy a new drive and enclosure. 

Don't understand why we would set the box up to take an external drive and then use eSata to make it difficult for some folks that don't understand to hook up a Drive before I switched back to Directv I asked if I could use an external drive and was told yes just plug it in. now it seems this is not the case.  if I can find one off the shelf with the eSata plug what is my size limit ?

    Box is Model HR44-500  Thanks in advance for any help.