A strain gage extensometer is a mechanical device which measures strain on a specimen which has been subjected to a load, usually via a materials testing machine.  The extensometer is physically attached to the specimen and the measurement of strain is performed by one or more strain gages attached to the contacting arm of the extensometer.  As the load on the specimen is increased during the test so the resistance of the strain gauge changes proportionally to the deflection of the extensometer arm.  This change of resistance is then measured by the electronics of the testing machine and converted to a strain value.

• The measuring systems feature very good linearity, with correspondingly reliable results.
• Gage lengths are adjustable from 10 to 100 mm, allowing flexible use for different specimen strengths.
• Light, miniaturized construction, well-suited to shorter specimens.