Wash the banana peppers and cut off the stem ends. To seed them, run a chopstick around the inside of each whole pepper to loosen the core, then tip the seeds out.
Slice the peppers into rings about 1/4 inch thick. For extra crunch, soak the rings in ice water for about an hour while the canner heats, then drain them well.
Heat the water bath canner, and keep the jars hot until you fill them.
Combine the cider vinegar, water and salt in a stainless steel or enamel pot. Bring to a boil, stirring until the salt dissolves.
Put the Pickle Crisp and the mustard and celery seed, if using, in the bottom of each hot jar. Pack in the pepper rings tightly, leaving 1/2 inch headspace.
Ladle the boiling brine over the peppers, leaving 1/2 inch headspace. Remove air bubbles and top up the brine if needed. Wipe the rims and apply the lids and bands fingertip tight.
Set the jars in a water bath canner of hot water, about 140 degrees F, with at least 1 inch of water over them. Bring to a full rolling boil, then process half pints and pints for 10 minutes or quarts for 15 minutes, adjusting for altitude (see notes).
Turn off the heat, take the lid off the canner, and let the jars sit in the water for 5 minutes before lifting them out.
Cool the jars undisturbed for 12 to 24 hours, then check the seals and store them in a cool, dark place. They're ready to eat in 2 to 3 days.