A centesis instrument, wherein a patient applies a contact part to a palm, a finger, or an arm in the state of gripping an outer tube by hand and presses the outer tube against its measured portion. A third coiled spring is compressed to increase spring power. When the outer tube reaches a prescribed...http://www.google.com.au/patents/US8147425?utm_source=gb-gplus-sharePatent US8147425 - Centesis instrument
