JLW, get the largest GAUGE you possibly can.
Syringes are sold with a few numbers; they are:
CC (sometimes ML) - how much the barrel will hold. Anywhere from .5 to 10, though .5, 1 & 3 will be the most common (go for 3cc if you can, otherwise get the 1cc)
inches - 3/8, 1/2, 5/8, 7/8 -...