Articles formed from powders containing tungsten and at least one binder. Associated electronics energize and monitor the probe, detect cardio-rhythmic fluctuations therefrom, and process digital data over a prescribed window to produce a non-invasive, qualitative or quantitative measure of the subject’s circulation. The operational guide assembly includes a support arm bracket having the tool support bracket connected therewith and a support arm extending therefrom at an angle normal to the mounting assembly, a pair of interface guide posts with retainers, and an interface tensioning mechanism including a slotted two level shaft. The validation indicator may additionally be stored in the metadata for the header block and it may be stored in header block itself. This output may be proportional to the level on the input signal. The tumbler springs are not accessible from the keyway of the lock and are more powerful than the sidebar springs.