Solution

The NI 9926 Quarter Bridge Completion Accessory is a bridge completion module used for strain gauge measurements, containing a resistor identified as R3 in the figure. Here are the main differences between the two models:
PN:786990-01 (Standard Type): Resistor Accuracy: 0.1%
PN:786990-02 (High Accuracy Type): Resistor Accuracy: 0.02%
The primary difference lies in the accuracy of the internal resistor. The high accuracy type (PN:786990-02) is suitable for applications where more precise measurements are necessary.