Needles on these are not uniformly sharp
I thought I would save a couple bucks buying the economy box. (The same quantity in the Monoject brand was a few bucks more, but not a lot.) However, the needles are definitely not as sharp as the more expensive sets. They are one use only. They are not meant to be used to draw a carrier from one vial, stick it into another vial to rehydrate a vaccine and then inject into a dog. By that time the needle is dull. If you are only drawing from the vial to the dog, they may be okay, but not in the first scenario. You can feel a marked difference in the amount of pressure needed to get the needle into the second vial, and then into the animal.