blood donor before, the diameter of the needle is (--) that big; the needle is HUGE (as far as i am concerned). Anyhoo, when u go to give blood, they swab the area with iodine - wiping(scrubbing) it clean. the chick yesterday did that and left the iodine on my skin; it's a dark brown liquid like substance. After all that, she had no problems and stuck the needle in with ONE shot - NO PROBLEMS, normEl, normEl. The blood flowed with no issues and i was actually done in 10 minutes!!!