A testing apparatus comprising: a spring component (220, 370) extending from a first spring end portion to a second spring end portion and having a spring intermediate portion, the spring intermediate portion having a spring inner diameter, the spring component (220, 370) including a coiled wire defined in part by a wire diameter; at least one testing component including a first elongate electrically conductive plunger (130, 312) extending from a distal end portion (152, 316) to a proximal end portion and having an intermediate portion (156, 317) therebetween, the first plunger (130, 312) disposed within the spring component (220, 370); the intermediate portion (156, 317) of the first plunger (130, 312) having a central longitudinal axis (142, 320), and defined in part by an intermediate outer dimension; the first plunger (130, 312) including a spring latch (182, 330), the spring latch (182, 330) including a hook portion disposed at the distal end portion (152, 316); and the distal end portion (152, 316) has a distal outer dimension at a base of the hook portion disposed at a greater distance from the central longitudinal axis (142, 320) than the outer dimension of the intermediate portion (156, 317) such that the hook portion encompasses a portion of the coiled wire when the testing component is in an uncompressed state, characterised in that the intermediate portion (156, 317) of the first plunger (130, 312) is configured and sized to bias the hook over the coiled wire when the testing apparatus is in an uncompressed state and the hook is free from the coiled wire when the testing apparatus is in a compressed state. a spring component (220, 370) extending from a first spring end portion to a second spring end portion and having a spring intermediate portion, the spring intermediate portion having a spring inner diameter, the spring component (220, 370) including a coiled wire defined in part by a wire diameter; at least one testing component including a first elongate electrically conductive plunger (130, 312) extending from a distal end portion (152, 316) to a proximal end portion and having an intermediate portion (156, 317) therebetween, the first plunger (130, 312) disposed within the spring component (220, 370); the intermediate portion (156, 317) of the first plunger (130, 312) having a central longitudinal axis (142, 320), and defined in part by an intermediate outer dimension; the first plunger (130, 312) including a spring latch (182, 330), the spring latch (182, 330) including a hook portion disposed at the distal end portion (152, 316); and the distal end portion (152, 316) has a distal outer dimension at a base of the hook portion disposed at a greater distance from the central longitudinal axis (142, 320) than the outer dimension of the intermediate portion (156, 317) such that the hook portion encompasses a portion of the coiled wire when the testing component is in an uncompressed state, characterised in that the intermediate portion (156, 317) of the first plunger (130, 312) is configured and sized to bias the hook over the coiled wire when the testing apparatus is in an uncompressed state and the hook is free from the coiled wire when the testing apparatus is in a compressed state.