The 803-C Invar Kit is designed as a multipurpose kit. It is often used as a scale extension tool - precisely extending the range of standard optical tooling scales for accurate measurement of larger dimensions, or to access previously unreachable points. It is also used with calibration scales or scaling artifact for three dimensional measurement systems.

Invar tubing is great for metrology because it has such a very low coefficient of thermal expansion, which effectively eliminates changes in length due to handling or environmental changes. This is particularly beneficial when measuring a system in its "hot" or running state.

The Invar tubing in the 803-C kit is manufactured to its stated length within ±0.0001". The Invar tubing components are hand-picked so that the total Invar tube stackup error does not exceed the stated maximum. This means that you can connect all of the tubes found in a kit together end-to-end, and the stack will maintain the total length within the stackup error. (The table above summarizes this information.)Individual components may be assembled to produce lengths from 1" to 112", in 5" increments. The end of each invar tube allows measuring to the tangents of shafts, and a tooling ball contact point offers the best repeatability on most machine surfaces. A special concave tip is included for use with tooling ball applications. The table below specifies all included components.