The strength of the reed is the issue. If you are an adult beginner, I usually recommend 2.5 reeds. If you rent or purchase a new instrument, it will likely come with one #2 reed. That's fine for starters, but you should move up to 2.5's on the first purchase. You can usually purchase them in either packs of 5 or boxes of 5 or 10 reeds. Get the cheap brand for starters. No sense in buying the expensive reeds until you are ready for them. Over the first six months or so, start the transition to #3 reeds.
Randy
jazz books
www.randyhunterjazz.com 
