Abstract: This invention concerns a resilience testing gauge and a resilience testing system, which includes the gauge, suitable for testing the seal quality of partly inflated bags. This invention also concerns a method of testing the seal quality of partly inflated bags using the resilience testing gauge. The gauge employs a first (2) and a second (3) beam cantilevered from a rigid block (4). In use the rigid block (4) is vibrated and one of the beams (3) is brought into contact with the article under test. The phase responses of the two beams (2 and 3) then provide information from which the test results can be determined.