These are two thin, round metal plates that are hit together to make a loud sound. See how you translated this in [1 Chronicles 13:8](../13/07.md). (See: [[rc://en/ta/man/translate/translate-unknown]])
The implied information is that they were to guard the entrance to the tabernacle. AT: "guarded the tabernacle gate" (See: [[rc://en/ta/man/translate/figs-explicit]])