Gromet

A grommet is a ring or edge strip inserted into a hole through thin material, typically a sheet of textile fabric, sheet metal and/or composite of carbon fiber, wood or honeycomb. Grommets are generally flared or collared on each side to keep them in place, and are often made of metal, plastic, or rubber. They may be used to prevent tearing or abrasion of the pierced material or protection from abrasion of the insulation on the wire, cable, line being routed through the penetration, and to cover sharp edges of the piercing, or all of the above.

A small grommet may also be called an eyelet, used for example on shoes, tarps and sails for lacing purposes. In electrical applications these are referred to as "insulating bushings". Most common are molded rubber that are inserted into small hole diameters up to 2" in diameter. There are many hole configurations from standard round to assorted U-shapes. Larger penetrations that are irregular in shape as well as long straight edges often use extruded or stamped strips of continuous length. These Continuous length materials are referred to as "grommet edging".

These are quite common in applications that range from telecom switches and data center cabinets to complex and dense wire/cable and even hydraulic tubing in aircraft, transportation vehicles and medical equipment.

Grommets are used to reinforce holes in leather, cloth, shoes, canvas and other fabrics. They can be made of metal, rubber, or plastic, and are easily used in common projects, requiring only the grommet itself and a means of setting it with a punch, a metal rod with a tip. A simple punch, often sold with the grommets, can be struck with a hammer to set the grommet. It can also be set with an electronic, pneumatic, or gas-powered machine. There are also dedicated grommet presses with punch and anvil, as shown in the picture, ranging from inexpensive to better-quality tools, which are somewhat faster to use. They are used to strengthen holes; in footwear for boot and shoe laces, in laced clothing such as corsets, and in curtains and other household items that require hanging from hooks, as when they are used in conjunction with tensioner rods for shower curtains. The grommet prevents the cord from tearing through the hole, thereby providing structural integrity. Small grommets are also called eyelets, especially when used in clothing or crafting. Eyelets may be used purely decoratively for crafting. When used in sailing and various other applications they are called cringles. Sometimes field workers may refer to them as grunyons.

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Wikipedia