From an REA auction, which verifies the previous information:
"During a single week in 1928 (August 6th-11th) Fro-Joy Ice Cream issued a six-card set, with each of the six cards featuring Babe Ruth. The backs of these cards invited youngsters to submit (by mail) a complete set in exchange for a large (8-5/8 x 12 inches) premium card. When this special premium card was sent by Fro-Joy to kids, the original six cards were not returned. In their place Fro-Joy sent an uncut sheet of the complete set of six cards, which featured additional advertising printed below the cards, and instructions on how to cut out the cards printed above.
The printing quality of the uncut sheets was slightly different and of lesser quality than the individually issued Fro-Joy cards, but were particularly neat looking in an uncut form with the extra advertising. The blue-tinted premium card was printed on a completely different and very unusual stock. One of the problems for collectors that has developed over the past twenty-five years is that for some reason literally millions of reprint Fro-Joy cards and sheets have been printed and are circulating. It's gotten to the point where it's hard to go to a flea market and not see them, and collectors are now so wary of the issue, and confused by the reproductions, that they now tend to just shy away from the set completely. Some grading companies have even stopped grading them. In the 1970s, before there were any Fro-Joy reprints, a single card could cause a riot at a card convention. No one had them! They were so rare that most collectors didn't even know what they looked like. An exciting find of a couple of hundred authentic cards in the late 1970s satisfied the most advanced collectors, but soon after reprints became so common that Fro-Joys understandably began to get a bad reputation. As time passed, some of these reproductions even had some age to them, confusing collectors all the more. Since the 1980s it appears that the printing presses have never stopped running on the reprints, both for individual cards and sheets. There are millions of them! But there also exists a small number of authentic examples.
Interestingly, the blue-tint premium card (which has an embossed bevel edge and is printed on a very unusual stock) has never been reproduced. We have seen only about a dozen authentic Fro-Joy uncut sheets (each with an accompanying premium) in all our thirty-seven years.
Usually the authentic sheets are accompanied by a Fro-Joy premium, as they were sent by mail together. This pair also includes the original Fro-Joy mailing envelope in which they were sent. The premium is in Vg-Ex condition with some very minor creasing in three of the four corners. The advertising section surrounding the cards on the sheet has some minor creasing and corner wear, and the bottom left corner has some chipping, but the large border has protected the actual cards on the sheet from most of the wear, leaving the six cards in overall Excellent condition. The original mailing envelope (12.5 x 9.5 inches) is addressed to Lorin Carter of Great Barrington, Mass. Total: 3 items (uncut sheet, premium, mailing envelope)."
http://www.robertedwardauctions.com/.../2008/516.html
Here's the blue tinted premium and the sheet from that auction (couldn't make them larger):
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