There are varied configurations for rubber grommet as customers give many kinds of requests and the grommets are customized for them. Many good companies use advanced manufacturing techniques to mold low volume to high volume custom grommets using all types of rubber polymers.
Wire Grommet to protect the wires are commonly used by the companies to protect their wires. The rubber acts as an insulator and can also be used as flow restrictors. Similarly there is demand for the logo grommet by various brands. Logo Grommet can be used to enhance a product and brand as company logos can be cut into the mold to show on various parts. This can be used by a brand to increase their marketing reach.
The Push-In grommets are used to fill in a hole thus they have an undercut and ribs on the side to stop the part and give extra interference when it is pushed in, respectively. Rubber polymers can be bonded to substrates like metal or plastic to create bonded grommet as the bonded grommet helps to remove the assembly steps & create a complete seal.
Ul-50 Grommet made from silicone is tested under the UL JMLU2 standard for gasket and seals using the UL 157 testing protocols which is mainly used for electrical enclosures. These are usually made by companies as they create grommets for their clients.
It is best to contact a company that specializes in custom grommets as in this way the exact demand is met. One can provide their custom applications, the configuration or a non-standard size grommet they might be needing.