When sourcing feed sensors, you must prioritize capacitive sensors or mechanical micro-switches depending on your system. Key specs include a sensing distance of 0-20mm (adjustable), an IP67 waterproof and dustproof rating to withstand harsh barn environments, and a wide voltage range (typically 90-250V AC or 10-30V DC) to ensure compatibility with various control boxes. Look for sensors with a built-in time delay function (0-2 hours) to prevent the motor from frequent starting and stopping, which extends the equipment's lifespan.