A retractable instrument in accordance with the disclosure advantageously has a simple construction and fewer pieces or sub-assemblies than known retractable instruments. The retractable instrument includes a barrel that encloses a tool holder. The tool holder has an extension, and a tool extending from the distal end of the extension. A valve selectively covers the tool to protect the tool from environmental conditions. A biasing element is disposed between the valve and the tool holder, the biasing element biases the valve away from the tool holder. A movable closure assembly retains the valve on the extension and selectively allows the lid to open and close. The closure assembly includes a closure ring and a retention ring connected by one or more closure arms. The retention ring is disposed on the tool holder and the retention ring is prevented from sliding off of the tool holder by a retention stop.