Sash locks are locks that are attached to the inside of a window or door and are used to lock the window or door extra securely. They are often used in combination with another type of lock, such as a cylinder lock or a multipoint lock, to enhance security. Sash locks can work in a variety of ways, depending on the type used. Some sash locks have a pair of cylinders built into the lock and can be locked from the outside of the window or door. Other sash locks have a lever or knob that needs to be pressed down to lock the lock. Sash locks are an effective way to secure windows and doors against break-ins and can also help to protect them from weather and other environmental factors.