ST6900 Series case mounted transmitters interface directly with PLC, DCS and 4-20 mA input monitors. Their compact size allows for installation in tight places. Model ST6911 is 4-20 mA proportional to acceleration while Model ST6917 is proportional to velocity. They feature Metrix proprietary Independent Polarity Terminals which allows for error-free wiring. These transmitters have the most stable detection circuit available due to built-in protection against temperature shock and high accuracy at low frequencies by preventing the "ski slope" problem.