Presto top load tester is a device used to measure the compressive strength of a material or a container under a specified load applied from the top. This type of tester is commonly used in the packaging industry to test the strength of containers such as bottles, jars, and cans. A top load test is a type of test that measures the compressive strength of a material or a container under a specified load applied from the top. This test is commonly used in the packaging industry to test the strength of containers such as bottles, jars, and cans. A top load tester for pet bottles is a specialized type of top load tester designed to test the compressive strength of PET (Polyethylene Terephthalate) bottles. PET bottles are commonly used in the packaging of carbonated drinks, water, juices, and other beverages.