A drilling term.

--------------------------------------------------
Note added at 5 hrs (2015-09-05 00:18:53 GMT)
--------------------------------------------------

Downhole Pressure Gauges
Signature Quartz Gauges
Signature quartz gauges consistently deliver accurate, high-resolution pressure measurements in any environment. Whether testing operations involve high temperatures rising to 410 degF, high pressures reaching 30,000 psi, or any other rugged downhole conditions, Signature gauges acquire high-quality pressure data for your entire test duration.
http://www.slb.com/services/characterization/testing/drillst...
ccccccccccccccccccc

Downhole Pressure and Temperature Gauges
SolarOptic™ Gauge is a fiber-optic based permanent pressure and temperature gauge designed for accurately sensing pressure and temperature under downhole conditions in the Oil and Gas industry. The downhole gauges provide real-time data to help optimize hydrocarbon production throughout the life of the well.
http://www.halliburton.com/en-US/ps/pinnacle/fiber-optic-mon...
cccccccccccccccccc
The Tendeka electrical monitoring system comprises a range of downhole pressure gauges and surface equipment which provide high-resolution permanent
http://www.tendeka.com/products/guardian-pressure-gauges
ccccccc

Datacan specializes in manufacturing and design of down hole pressure gauges, shut in tools, and permanent pressure monitoring recorders.
http://www.datacan.ca/home.php