The main advantages are:

• No power supply required. No current consumption in open state with real galvanic isolation and no voltage drop in closed state.
• Works in difficult environments: wide temperature range, insensitive to dust, water projections, ...
• The detection distances can be very large. They will depend mainly on the magnetic sensitivity of the bulb and the power of the magnet as well as the magnetic environment of the couple Reed Switch + Magnet.
• Very economical compared to all other technologies.