We have all been in this standoff. You are at a card show, standing at a dealer’s table with a slab in your hand. You know the last eBay sale was $100. The dealer knows the last eBay sale was $100.
But when you ask for an offer, he hits you with the standard line: “I can do 65%.”
His argument is always the same: “I have to run a business. I have to wait for this to sell. I’m taking on the risk.”
For a long time, that was a valid argument. But what if you could prove, with data, that there is significantly less risk? What if you could prove that the slab in your hand is mathematically equivalent to a $100 bill?
At Mantel, we realized that “comps” (recent sales prices) only tell half the story. Knowing what a card sold for doesn’t tell you how easily it will sell again. So, we invented a new metric to solve this specific problem.
It’s called SLAM (Secondary Liquidity & Momentum).
The “Cash Equivalent” Score
The philosophy behind SLAM is simple: How close is this card to straight, cold, hard cash?
If a card has a massive SLAM score (90+), it means the market for that card is so liquid, so consistent, and so active that holding the card is basically the same as holding the money.
This changes the negotiation dynamic entirely. If you walk up to a vendor with a card that has a SLAM score of 92, you don’t have to accept 60% or 70% of the value. You can look them in the eye and say, “This card trades every single day with almost no price fluctuation. It is as good as cash. I’d like 85% to 90%, not 70%.”
How It Works: What the SLAM Score Actually Measures
We didn’t just want another price guide. We wanted a “confidence” guide. The SLAM score (0-100) helps you identify which cards are actively traded in the hobby by measuring three specific things:
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Tradeability: This is the heartbeat of the score. We combine sales volume with price stability over time. It answers the question: If I list this today, will it move at the last comp, and will it hold its value?
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Consistency: A card that sells once for a million dollars isn’t liquid; it’s a lottery ticket. SLAM rewards cards with steady sales volume and “comp retention”—meaning the card holds its value transaction over transaction.
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Accessibility: This is key. We purposefully filter out ultra-rare cards (like 1/1s or super short prints) to spotlight the cards everyday collectors actually buy and sell. If a card is too rare to have a market, it can’t have a SLAM score.
Slam score examples
What it’s not
As important as it is to understand what the SLAM score measures and how it’s used, it’s equally important to discuss what it’s not.
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It is NOT a Price Predictor: A high SLAM score doesn’t mean a card is about to go up in value. It means the card is highly liquid. You can have a card with a 99 SLAM score that is trending down in price, but because it sells 50 times a day, you can still exit that position instantly.
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It is NOT Financial Advice: SLAM provides data transparency, not investment recommendations. A high score means a card is liquid, not that it is a guaranteed profit maker. Always do your own research before spending your money.
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It is NOT a “Hype” Meter: Hype is often based on media buzz. SLAM is based on cold, hard data. If everyone is talking about a player but nobody is actually buying their cards, their SLAM score will usually be low.
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It is NOT for 1-of-1s: We intentionally filter out ultra-rare cards like 1/1s or super short prints. Why? Because you can’t measure “liquidity” on a card that only appears once every five years. SLAM is for the cards you actually see at shows and in shops.
Who is this for?
SLAM is for anyone who wants to know their exit strategy before they buy. For sellers it helps you negotiate a better price, for buyers, it significantly reduces the risk of cards you buy.
If you are buying a card with a high SLAM Score (80-100), you are buying the card equivalent to cash. These are the cards that are gone as soon as they are listed, you can buy them on Saturday and sell them on Sunday. Here is how we are thinking about the different levels:
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Gold Score (90-100): This card is as close to cold hard cash as you can get.
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Green Score (70-90): This is liquid. High demand, stable price, easy to move.
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Yellow Score (40-69): This is inventory. It will sell, but you might need patience or price flexibility.
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Red Score (0-39): This is a “Collection Piece.” Buy it because you love it, not because you need to flip it tomorrow.
The hobby is evolving and so will the SLAM score. We are looking for your feedback right now to improve the metric and make it something that truly helps both sides of the hobby. Head over to the Mantel app, add cards to your mantelpiece and see what scores you get.
So many apps have already mastered the art of tracking prices. Now, it’s time to master the market itself. If you’re looking to flip; buy for liquidity. If you’re looking to hold, collect what you love.
