DIN rail is standardized mounting bracket for electrical equipment. There are wide arrays of terminal blocks, circuit breakers, relays, power supplies, and heatsinks that are all designed to be DIN mountable. This particular rail is top hat type (EN 50022) rail.
|Standard||EN50022 - 35x7.5|
If you need to connect multiple wires together in a neat an organized way, these DIN terminals will help a lot. They snap directly onto this size of DIN rail and can be easily rearranged and labeled.