Sanwa Supply RJ-45 Coupler ADT-EX-5N (Category 5) Used item. https://www.sanwa.co.jp/product/syohin?code=ADT-EX-5N Used for connecting LAN cables. While it supports CAT5, it also worked for extending CAT5e and serial cables. Can also be used when joining and pulling cables. Due to its thickness, it will be shipped in simple packaging.