Jumpers consist of metal bars or conductors used to close, open, or bypass part of an electronic circuit. Jumper pins (points to be connected by the jumper) are arranged in groups, with each group having at least one pair of contact points. Jumpers must be electrically conducting, but they are typically covered by a non-conductive plastic, to avoid risks of electric shock and also to stop from accidental shortages. These jumpers are available in a wide range: from 2 pins to 20 or even 50 connection pins. There are different styles of jumpers based on the terminal block type in use.