【Communicate without speaking】DO NOT DISTURB, PLEASE KNOCK, IN A MEETING and OUT OF OFFICE, help to inform the exact status of your office . You can easily switch between the four options. The status will still remained unless you change it manually. 【Easily identified】5 inch diameter. Four states in different colors , so you can distinguish different sign content easily. 【Convenient to install】Magnetic and adhesive sticker option. Convenient to install and no residue left when removed. Works on all occasions , stainless steel, wood cabinet doors etc. 【Multiple uses】Suitable for office room, conference room, or any room that needs privacy. 【Quick changes】One sign can show 4 states. Only put it in a horizontal position, the slider can slide easily to display smoothly and quickly.