Abstract: Instrument protective apparatus comprising a body having first, second and third sections, the second section being disposed between the first and third. A first chamber is formed between the first and second sections and divided by a first diaphragm. A second chamber is formed between the second and third sections and divided by a second diaphragm. Fluid communication means are provided between the portions of the first and second chambers defined by the second section and the first and second diaphragms. The fluid communication means and communicating portions of the first and second chambers form a force transfer liquid reservoir substantially filled by a force transfer liquid. A pressure reaction fluid reservoir in the third section is at least partially defined by the portion of the second chamber defined by the third section and the second diaphragm and substantially filled with a pressure reaction fluid.