Who is that masked man that's the focus of one of the most popular non-sports sets ever issued?

That would be the Lone Ranger, the star subject of a 48-card, 1940 Gum Inc. issue that's still highly coveted nearly seven decades after its release.

"The Lone Ranger set has got to be in anyone's top five for all-time classic, non-sports sets," said Jim Damiano, who owns the PSA Set Registry's No. 4 Current Finest set.

Distributed in penny packs, cards in this venerable offering measure 2-1/2" by 3-1/8" and feature colorful drawings of the Lone Ranger's adventures.

"The appeal of this set to me is the beauty of the cards," explained Brian Karl, proud proprietor of the registry's No. 2 Current Finest set. "The artwork on these cards is just amazing to me."

Damiano concurs.

"This set is the classic of the classics. When you pick up a card and look at it, it jumps out at you. It screams that it's a classic," he said.

Copyright information can be found on the fronts and backs of these cards. The backs also boast text describing the scene on the card front and the card number. Like the Gum Inc. Superman set from the same year, the high-number cards (#37 to 48) are the most elusive.

"The high-numbers are next to impossible," said Damiano.

Marty Quinn, who owns the registry's top set, agrees.

"Over the last 10 or 15 years, collectors have also realized that numbers 24 to 36 are also very tough. It's really the last 24 cards that are tough," he said.

Hobbyists were unable to provide a definitive answer as to why the high-numbers are so difficult to obtain. Quinn suggests that the cards were likely printed in series and fewer were printed of the final series.

Card #37 - with the caption His Father's Son - has been submitted to PSA the fewest number of times. Of the 14 sent in, just one has been graded as a high as PSA NM-MT 8. Five others have been tabbed as PSA NM 7s, with one selling for $164.05 on eBay in January 2009.

Silver's Vigil - the last card in the set - is also evasive. Karl notes that this card was subjected to additional wear because it was on the bottom of card stacks. Of the 15 submitted, there have been two PSA NM-MT 8s and two PSA NM 7s.

The set's first card - A Silver Bullet Stops A Hanging - suffers from similar condition woes, but is even more difficult to uncover in high-grade.

"That was the card that was handled first. That was the card that had the elastic go around it. If you ever do see it, it's all creased up. A PSA (VG-EX) 4 or (EX) 5 is fantastic on that card," said Damiano.

But hobbyists say that high-grade versions of any card from this set are rare in top condition.

"When you see these cards, they're well-handled. Everybody loved them, but they're creased and they don't grade very well. To find something that's really high-grade is practically impossible," said Damiano.

Quinn says these cards also tend to showcase discoloration.

"The cardboard they used is susceptible to toning," he said.

Similar to the 1940 Gum Inc. Superman set, these cards also sometimes exhibit a print line on their fronts.

Collectors could also send in wrappers with money to receive a series of five, eight-by-10 Lone Ranger Premiums (R83A). These collectibles are highly coveted but very rare.

"I've only seen them a couple of times and I've never owned one," said Damiano.

Karl agrees.

"If there are any out there that are in good shape, I'm sure that they're in private collections, stored away and we may never see them," he said.

The first premium in the series is the most difficult to track down. In top condition, these premiums will command $300 to $400 a piece, says Quinn.

Through radio programs, TV shows, books and films, the Lone Ranger has remained popular for more than 75 years. There are also rumblings of a new movie being produced with Johnny Depp in the role of Tonto.

"The Lone Ranger and Superman, they're American icons," said Quinn. "The Lone Ranger set has great investment potential. I don't think you'll see a big unopened find of Lone Ranger cards, where it's just going to flood the market and ruin the value. I think a set like this is always going to keep its value."