Biblically, the infant's father (avi haben) is commanded to perform the circumcision himself. However, as most fathers are not comfortable or do not have the training, they designate a mohel. The mohel is specially trained in circumcision and the rituals surrounding the procedure. Many mohelim are doctors or rabbis (and some are both) or cantors. However, all are required to receive appropriate training both from the religious and medical fields.
Traditionally, the mohel uses a knife and not scissors to circumcise the newborn; glass was never used. Today, doctors and some non-Orthodox mohalim use a perforating clamp before they cut the skin. The clamp makes it easier to be precise and shortens the recovery time. However, Orthodox mohalim have rejected perforating clamps, arguing that by crushing and killing the skin it causes a great amount of unnecessary pain to the newborn, cuts off the blood flow completely, which according to Jewish law is dangerous to the child and strictly forbidden, and also renders the orlah (foreskin) as cut prior to the proper ritual cut.
Under Jewish law, a mohel must draw blood from the circumcision wound. Most mohels do it by hand with a suction device, but some Orthodox groups use their mouth to draw blood after cutting the foreskin.
Shaky the Mohel --Charles Levin --After circumcising Jerry's finger during a bris, he blames Jerry, claiming he flinched. Jerry later derisively refers to him as "Shakey the Mohel" and claims that the mohel got his license from a matchbook. -- "The Bris"