Beckman Model M pH Meter Open Access: 
Wooden box with handle at top and metal latch closure at front; interior: instructions for use printed on paper and inset into box lid; top face: window at center reveals pH scale "7-14" and millivolts "0-400"; control knobs for "AP" and "STD" at right and left; power switch at bottom center of face; compartment for electrode (attached) at right.
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Staff photographer</div>
2016
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