WHEN I NEED BLOOD WORK DONE, THE PHLEBOTEMIST HAS TO USE A BUTTERFLY NEEDLE ON ME. IT WORKS EVERY TIME. I CAN ONLY USE ONE ARM, BECAUSE I HAD BREAST CANCER IN MY RIGHT BREAST. MY DOCTOR SAID I HAVE TO AVOID GIVING BLOOD IN MY RIGHT ARM BECAUSE OF POSSIBLE INFECTIONS. THE LYMPH NODES WERE REMOVED UNDER MY RIGHT ARM, AND THAT FIGHTS INFECTIONS. I KNOW, TOO MUCH INFORMATION. BUTIT IS GOOD INFO. I AM A CA SURVIVER 10 YEARS NOW!!