MB-18 Polyethylene Water Meter Box Approximate Measurements 17" x 15" x 12" and tapers to 21 1/2" x 20 1/2" x 12" The new MB-18 water meter box is designed to allow two meter sets to be in the same box with only one inbound supply line. The MB-18 box is versatile with a choice of one, two or possibly three sets of mouse holes. The MB-18 is very durable with the new rib reinforced design allowing this sturdy box to withstand over 20,000 pounds in an H-20 style test. The standard depth of this box is twelve inches and can be either ordered with or without the bottom setting ring. The box accommodates a standard 15"x17" lid.