So if the pitcher calls out a number from her wristband, would she have to proclaim that number prior to stepping to the pitching plate, or could she do it once she steps to the plate?
I've used these over the last four years and absolutely love them.
I've a random number generator script I wrote... outputs the range chosen randomly to an excel spreadsheet. No two are ever the same... and I'll generate four cards per game/per pitcher as well as my master sheets in less than 10 seconds... and I use perforated card stock to make pulling them off the sheets quicker. My entire team takes the signal... hell, at times I'll just say the numbers out loud... with zero worries of someone figuring out the sequence, because it never appears more than once. My defense really benefits from knowing the call... which is a huge benefit more coaches should utilize, IMO. Have them for my offense, too. Every once in awhile we'll 'accidently' leave a card in the dugout after a game... and get a bunch of chuckles at the coach who finds it and thinks he/she knows all the calls when we face them later. There's 150 offensive and defensive plays per card... all randomly generated... and there's more than pitch type/locations on there, too...
Learning the cards is so much simpler... and really helps maximize practice time as well as the time between calls and misreads in games. Switching out cards takes 10 seconds... and we all put our hands (bands) in the middle... with each player checking their teammate to their right... then say a little diddy as we take the field.
We had a girl on DD's team use one, not with a 3 number system, just because she wanted to.
Her pitcher had 2 pitches. ;-)