A flesh tunnel, also known as a spacer, is a type of body piercing jewelry. It is also sometimes referred to as a spool, flesh, earlet, expander or eyelet. Wearers generally use them to show off the process of stretching that they have gone through.

Flesh tunnels are hollow tunnels, usually used in stretched or scalpelled piercings. Flesh tunnels are made in smaller gauges however the smaller the gauge the smaller the effect to see through the plug becomes. Some people may choose to wear flesh tunnels instead of flesh plugs because they weigh less, especially at larger sizes. Flesh tunnels may be worn with a captive bead ring or other object passed through them.

Flesh tunnels can be made from many materials. Surgical steel, titanium, Pyrex glass, silicone, acrylic plastic and a variety of natural materials, including bone, horn, amber, bamboo, stone, and wood all are common materials for flesh tunnels. Flesh tunnels, like flesh plugs, may contain a variety of decorative inlays or semi-precious stones. Some flesh tunnels have flares to keep the jewelry from falling out. If there are no flares, grooves may be cut near the edges to allow rubber or silicone o-rings to hold the jewelry in place. The back of the flesh tunnel may also screw off. Some flesh tunnels have internally threaded backings, as externally threaded pieces can rip freshly stretched ears.

Flesh tunnels are often worn in the earlobe, but other soft-tissue areas that are pierced can be fitted with these tunnels. In these cases the length of the tunnel might be different. Examples are the nasal septum and nipples.

The actual origin of flesh tunnels, plug piercings, and body plates derived from the many tribal groups of the world. Examples would be (but not specifically) the people of Myanmar, Africa, and some Native groups. Different sizes, materials and colors determine the difference between certain tribes. The flesh tunnels symbolize different roles in their societies, for different groups, however, during the ancient Egyptian New Kingdom, both sexes wore a variety of body jewelry, including earplugs/tunnels, as in this current time, they and we more often wear them a fashion statement.