I saw in Camerons post a mention of a "porper" clip. What's that? Google turned up with card clips by "Joe Porper", but Porper clips sound more specific than that.
Thanks for the info!
Joseph Porper is a man who started out making professional-grade billiards equipment and related tools. He was inspired by a trip to a magic shop to create professional-grade magicians' stage props and gimmicks. The one item he's most well-known for in this corner of the Internet is his famous Porper Card Clip.
Porper card clips are meant to hold a deck of cards in the box, providing pressure to the front and back in order to keep your cards as flat as the day you bought them. Prior to this invention, people had to use card presses - and since playing cards became so cheap to the common consumer, the popularity of card presses has fallen dramatically.
The original Porper clip is engraved on the spine with his signature and has a spine with a sort of "M" shape when seen from above - that shape acts like a spring when you slide your deck into it. The front and back walls of the clip curve slightly outward at the edge furthest from the spine, making it easier to slide a pack of cards into it. Later, when people selling them started to apply assorted coverings on them (ordinary and exotic leathers, carbon fibers, cork, etc.), he created a simpler version of the clip with a flat spine. Some of the custom clips he's made for people like David Blaine or the Buck twins will have their company logo somewhere on it as well, often inside the spine.
Both designs are not bent from sheet metal, but instead are carved out of a solid block of aluminum, meaning there's practically no risk of a stress fracture in the spine under ordinary use; bending sheet metal creates stresses and weaknesses in the metal. The thickness of the aluminum makes it exceptionally sturdy - I'd wager that if you slipped a pack into one and ran it over with your car, it would still be intact and your cards would be undamaged. Simply put, Joe builds gear to LAST - his gear will probably outlive you!
As far as usage goes, there's a bit of a split. Some people, especially cardists, swear by them because they need completely flat cards. They put their cards through a lot of torture and they want them to last. There are others that don't like them for a few reasons. The tension created to flatten the cards also crushes the box, which is especially bad if you paid good money for a deck with an embossed, foil-laden tuck box - good for the cards, terrible for the boxes. Lastly, there's the "oddity" factor. Some magicians either don't use them or remove them before approaching a performance. The reason is that when your audience sees you pull a pack of cards out of a Porper clip, a Pack Jacket - basically, anything that magicians use but the public has never heard of - some people immediately think that the deck must be a "trick deck" of some kind.
I personally own a few card clips, but I find that I'm using them less frequently - I'll push a deck into my Porper clip if I have a few cards that got bent but not severely enough to crease and I have a clip made by Zenneth Kok that's not a Porper but is useful for certain card tricks.
Make sure if you buy one that's it's the real thing and not a counterfeit. I've noticed some counterfeits being sold by Asian-based accounts on eBay - they look the same but come in colors that the Porper clip was never made in and some forgers don't bother with replicating the signature on the spine..