TEC-HRO Distance Kit Individual Spacers With this spacers it is possible to vary the height of "TEC-HRO system 2.0", the sight-enlongation "TEC-HRO extender" or "TEC-HRO system Auflage" any old from 11 - 31mm in always 2mm-steps.If you don't need the complete distance-kit you could decide here which height you need.The height you can chose is the total height of the sight elevation when the spacer is mounted.