The link is the part of the nunchaku joining the two sticks. Links are either cord (also known as "rope" or "string") or chain. Depending on which link a nunchaku uses, the feel of it may be drastically different.
The connectors between the link and each cord are known as the joins.
Standard nylon is a popular cord material, although parachute cord (or "paracord") made out of multiple nylon threads is respected as a more durable material.
On corded nunchaku, the joins are made up of a series of holes used to string the cord with one of various stringing methods. The use of these holes depends on the stringing method. The most common and traditional hole pattern is one hole on the top of the head and two vertically spaced at the side, though a single side hole is also sometimes used.
The chain can be connected to the head of the nunchaku with a number of different joins: most commonly ball-bearing swivel, but also U-swivel, T-swivel, and simple screw mechanisms. Swivel mechanisms are more popular over screw mechanisms since the latter is more vulnerable to breaking and hinders the smoothness of rotation at certain angles of swinging. Though ball-bearing is most popular, the rarely available U-swivel is said by some to be superior.
In addition to link type, the length of the link is also a very important feature of nunchaku. Short links are preferred by practitioners of artistic, exhibitive martial arts such as XMA and Lissajous-do since they allow for greater control of spins. Long links are preferred by people using nunchaku for combat as well as by some traditionalists since they allow for greater reach while using the nunchaku as a weapon. Within freestyle nunchaku, link lengths vary between practitioners, though most use a standard link length of 3-4", which allows decent control without sacrificing the ability to perform certain techniques such as the wheel.
The cord of corded nunchaku tends to fray over time of spinning, weakening the link and causing a dangerous situation in which the link may break during a performance. To prevent this situation, some users of corded nunchaku coat the head of the nunchaku with wax or attach metal or plastic grommets to the head. However, corded nunchaku are easy to repair due to ability to restring them using various stringing methods. With proper care, the ability to easily restring corded nunchaku lessens the risk of the accident, since weak cords may be discovered and replaced before breaking.
The maintenance of chained nunchaku depends more on the joint than on the chain link itself. Low-quality swivels tend to rough and noisy after time of spinning. To prevent this situation, some users of chained nunchaku recommend using oil or other bearing lubricants on the swivel. Simple screw mechanisms can fail when the screw breaks or the hole holding the screw enlarges too much. For this reason, screw mechanisms are not so popular or recommended as swivels.