The Graham Field-1231 is a high-precision Schiotz-style tonometer from the Grafco line, essential for screenings of glaucoma and other conditions involving intraocular pressure. This manual instrument works by placing a plunger on the anesthetized cornea and measuring the resistance, which is indicated on a calibrated scale. Built from high-quality stainless steel for durability and hygiene, it comes complete with three standard weights (5.5g, 7.5g, and 10.0g) to accommodate different pressure ranges. The unit is housed in a protective, padded storage case to maintain the delicate calibration of the weighted plunger system.