1. Compatibility: 1/87 HO Model Train Test Track Module needs to work with roller test stand. It is adapted to 1/87 HO scale train models of most brands. 2. Function: Test Track Bearing (roller trolleys) can test the model train on the track or layout tracks. 3. Diagnostic Module: Single unit treadmill track is for testing/repairing 1:87 HO scale trains. It can analyze idling performance and movement to identify faults (Note: Train Not Included). 4. Expandable: Multiple units can be connected for diagnostic setups. The reliable base ensures structural accuracy for exhibitions or repairs. 5. Including: 1 Diagnostic Treadmill Unit. 6. Specification: Material: metal and plastic. 7. Size Chart: 5.12cm/2.02inch. 8. Package Includes: 1/87 HO Model Train Test Track Module. 9. Note: Slightly errors of 1-2cm/0.39-0.79inch differences may be allowed due to manual measurement.