when researching how to do injections I read that you're supposed to replace then needle after drawing from the vial before you inject, I was under the impression that needles and syringes come seperately and you can take off the needle. But the syringes and needles I got now come combined together. So after I draw the liquid from the vial, what should I do ? How can I replace the needle if everything I have is attached to a syringe. Should I just use the same one, or is there a way to transfer it to a new syringe ?