The image shows a bicycle mudguard, also known as a fender. It is a protective accessory designed to prevent mud, water, and debris from being splashed up by the wheels while riding a bike. 
Material: Typically made from durable, lightweight, and flexible plastic. 
Purpose: Keeps the rider and the bicycle's components clean, especially in wet or muddy conditions. 
Compatibility: Many mudguards are designed to be a universal fit for various bicycle types and sizes, such as 26 -inch bikes. 
Features: Some models include reflective tapes for increased visibility and safety, and they are generally easy to install.