The card I added to my collection today was of Rob Gronkowski. These parallels are the most insidious of the bunch. The blue, red, pink and prizm refractors are all very easily identifiable. The base refractors have a rainbow shine to them but they are not numbered. I've mistaken the refractors for the regular cards a couple of times. They do have the word "REFRACTOR" on the back of the card but they are not numbered (nor are the x-fractors) I believe I pulled about 7 or 8 of the refractors out of my two boxes so I'm guessing a collector can expect about 4 per box of these little beauties. Can't go wrong here with one of the best tight ends for a dominant team.