Limewood is also the material of choice for window blinds and shutters. Part K also includes safety requirements for automatic doors, barriers, shutters and gates. Most windows are fitted with a set of timber louvred shutters. The windows were covered by functional exterior shutters, which opened outward. The window shutters of oak were probably original. An active shutter 3D system uses electronic shutters. Decoration was provided by ornamental iron shutters and then wrought-iron balconies. Global shutter can also be used for videos as a replacement for rotary disc shutters. Both cannons were protected on all sides behind six exterior-mounted, heavy iron shutters. Solid wood shutters were used during cold seasons. This collection comprises twenty-two exterior house shutters that Lewis painted in the early 1940s. The shutters, and hatches in the plywood deck, are opened for public ringing. Finishing wood shutters is recommended for extended life. During the silent era projectors were commonly fitted with 3-bladed shutters. Interlocks, shutters, and warning lights are often critical elements of modern commercial installations.