the Hanna Checker Iron High Range HI-721. This compact and portable device is perfect for use in aquatics and can provide accurate results in just a few simple steps. With a range of 0.0 to 5.0 ppm (mg/L), this iron checker is ideal for monitoring and controlling iron levels in aquariums. The HI-721 also features a large, easy-to-read digital display and automatic shut-off to conserve battery power. With its affordable price and professional accuracy, the Hanna Checker Iron High Range HI-721 is a must-have tool for any aquatics enthusiast or professional.