Place these compact, portable pressure recorders anywhere a written record of pressure is needed. The durable velox PBT NEMA 4x-rated case protects against corrosion, windblown dust and rain, splashing water, and hose-directed water. Recorders are ideal for investigating and monitoring systems for gas, steam, and water leaks; documenting system pressure at water treatment/purification facilities; and measuring flow of water wells. Unique door closure ensures weather resistance. Recorder operates for up to one year on a single AA battery. On/off switch provides battery savings. Battery holder is located inside the door for easy battery changes. Note: these pressure recorders are not suitable for monitoring ammonia, acids, or other corrosive substances. 4 inch compact pressure recorders weather-resistant, NEMA 4x-rated enclosure withstands harsh outdoor environments compact 4 inch circular Chart records pressure up to 500 psi. Choose from 24-hour or 7-day recording times. Battery operated for easy portability.