For this reason, CAN uses 'bit stuffing' to maintain synchronization. Bit stuffing means that when too many dominant or recessive bits are sent consecutively to keep the bus synchronized, the transmitting node inserts an opposite-polarity bit. The resulting signal edge is used to establish timing synchronization at all nodes on the bus. Specifically, CAN requires that bit stuffing be applied after there is a sequence of five bits with the same polarity.