The Hard Drive Caddy is designed specifically for DELL OptiPlex desktop computers, including models 390, 790, 990, 3010, 3020, 7010, 7020, and 9020. Made of rigid plastic in a blue color, this caddy is dustproof and water resistant, ensuring the safety of your 3.5 inch drive. With its sturdy construction and compatibility with various DELL OptiPlex models, this caddy provides a reliable storage solution for your computer system.