An adjustable window roller is a type of window roller that can be adjusted to fit various types of windows and sashes. It typically consists of a metal or plastic wheel that rotates on a metal or plastic frame. The frame is attached to the sash, and the wheel sits in a track on the window frame.

Adjustable window rollers can be found in different types of windows, including casement windows, sliding windows, and double-hung windows. They are usually easy to install and can be replaced without having to replace the entire window. However, it is important to ensure that the replacement roller is the correct size and type for the window to prevent damage or malfunction.