The OTS PB and OTS AF insulating oil test sets are a range of automatic oil test sets that perform accurate breakdown and withstand voltage tests on mineral, ester, and silicone insulating liquids. All models have precision, shatter-proof test vessels that are easy to clean and provide repeatable results, whether they are used in the field or laboratory. They also have a transparent, shielded lid and a large test chamber, giving you easy access to the test vessel and allowing you see what is happening within the test chamber.