These ear gauge made from acrylic epoxy. Acrylic in piercing mostly used for plugs and tapers. Due to the material's slipperiness, it is widely used for stretching. A flesh tunnel is a hollow, tube-shaped variety of body piercing jewelry. It is also sometimes referred to as a gauge. A flesh tunnel is usually used in stretched or scalpelled piercings. Flesh tunnels are fashioned from a broad range of materials, including surgical steel, titanium, Pyrex glass, silicone, acrylic glass, bone, horn, amber, bamboo, stone, and wood. Flesh tunnels, like flesh plugs, may feature a decorative inlay or semi-precious stones. Some flesh tunnels have flares to keep the jewellery 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 jewellery in place. The back of the flesh tunnel may also screw off. A flesh tunnel may also have an internally threaded backing, as externally threaded pieces can rip freshly stretched ears.