Red Button Locks like the SAFEBOLT™ are equipped with visual indicators on the classroom side of the doors to show when the emergency bolt has been engaged.
{"Image Orientation": "Horizontal (normal)", "Image XResolution": "127/5", "Image YResolution": "127/5", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CC (Windows)", "Image DateTime": "2019:01:10 13:38:48", "Image ExifOffset": "164", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "324", "Thumbnail JPEGInterchangeFormatLength": "5216", "EXIF ExifVersion": "0210", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "1200", "EXIF ExifImageLength": "1200"}