Use this heavy-duty magnetic Garage Door Contact Switch on garage doors, roll-up doors and other doors or gates where it may be difficult to mount regular magnetic contacts. Smaller magnetic switches have a small operating gap where the contact and magnet must be within half an inch for reliable operation. While those switches are fine for most doors and windows in a home, they just won’t cut it for larger doors. These contacts can be as far as 2 3/4 inches apart and still operate.