How much is a sleeve of celery?

I was reading a recipe for Slow Cooker Rosemary Garlic Beef Stew and noticed that one of the ingredients called for a "sleeve" of celery. I've heard of a stalk of celery, but I've never heard of a sleeve. Here is the list of ingredients:

Ingredients

• ½ lb. (4 medium) carrots $0.55


• ½ sleeve celery $0.65


• 1 medium onion $0.36


• 2 lbs. red potatoes $1.00


• 2 Tbsp olive oil $0.32


• 4 cloves garlic, minced $0.32


• 1½ lbs. beef stew meat $9.06


• Salt and pepper $0.05


• ¼ cup all-purpose flour $0.04


• 2 cups beef broth $0.30


• 2 Tbsp Dijon mustard $0.24


• 1 Tbsp Worcestershire sauce $0.06


• 1 Tbsp soy sauce $0.10


• ½ Tbsp brown sugar $0.02


• ½ Tbsp dried rosemary $0.15


• ½ tsp thyme $0.05

How much celery do I need to add to the recipe?