Basic Action: The “Key” is essentially the older brother of the “box”. Rather than boxing all of your horses (where you win if they come in any order), keying allows you to more boldly back up your convictions about a certain horse by locking the horse into the top spot, and then using the other horses you sort-of liked in the race “underneath” in your exotic bets. For example, if you key the 6 horse over the 2, 3, 7 horses in a $1 trifecta, you would need the 6 (your “key horse”) to win and for any combination of 2,3,7 to finish in the second and third spots. Since there are 6 combinations involving the 2,3,7 finishing second and third, the cost of your ticket would be $6. Had you boxed the 6,2,3,7, the cost of your ticket would be $24 ($1 x 24 possible combinations involving four horses finishing in the top three positions).
Advanced Action: Keying is a helpful tool to cut down cost and it allows you to place more emphasis and concentrate your money on horses whom you believe have the strongest shots of winning on any given day. It also allows you to minimize cost when you want to add “bombs” (or long shots) underneath in your combinations, which could result in higher payouts.
The danger comes when you key a horse on top to win and, instead, that horse finishes second or third. It stings quite a bit when you could’ve hit a big ticket but you didn’t because you “locked” yourself into a “key” horse on top. Two pointers: Only key horses on top when you’re absolutely confident in them, and if you’re not positive and want to back-up (or insure) your key bet, wheel your key horse underneath in exotics. What wheeling underneath means is that you’ll make multiple other bets, in addition to your initial key of 6 over 2,3,7 bet. When you wheel the 6 in other spots, your tickets will look like this: A. 2,3,7 with 6 with 2,3,7 and B. 2,3,7 with 2,3,7 with 6. This way, if the 6 horse finishes in any of the top three positions, with 2,3,7 filling out the other two spots, you win.