KIMBLE® 45325A-50 KIMAX® Nessler APHA Color Comparison Tubes with Cap Stopper are a matched set. These Nessler tubes are ideal for color comparison and feature cap style stoppers that do not need to be removed to take readings. Shadowless bottom of each tube transmits undistorted light. Standard Taper cap style stopper. Graduated ring scale of any of the tubes within a matched set will not vary from that of any other tube within the set by more than 1.5mm for the 50mL. Replacement cap is 15182. Manufactured from 33 expansion, low extractable borosilicate glass conforming to USP Type I and ASTM E438, Type I, Class A requirements.