This Monoprice RJ-11 and RJ-45 Modular Plug Tester (108138) is a must-have for any computer enthusiast. It allows you to quickly and easily test your modular plug connections without any hassle. With its compact design and easy-to-use interface, you can test your plugs in no time.The tester is compatible with both RJ-11 and RJ-45 plugs, making it a versatile tool for all your testing needs. It features a durable construction that ensures long-lasting use, and its compact size makes it easy to store and transport. Whether you're a professional or a DIYer, this modular plug tester is a must-have for any toolkit.