Old type Wheel stop for HO and On30 gauge. Will fit Peco code 100 rail and other makes , though the slot may need widening for certain rail sections.
With some work can be adapted for heaver rail.
Supplied in 100 off bulk pack so sufficent for ends of 50 sidings.
Please note although it's fully modeled as in the render not all detail will print as drawn because it's too small - but then it's going to be hard see all that detail anyway !
Also note it's meant to have ribs on one side only !