NMRA Standards & Recommended Practices
Since 1935, the NMRA has developed Standards and Recommended Practices (S&RPs) so that model railroad equipment from different manufacturers and modellers can work together — track gauge, couplers, wheel profiles, electrical systems, and more.
- Standards (S) — mandatory specifications approved by the NMRA Board
- Recommended Practices (RP) — guidelines for best interoperability, not strictly mandatory
- Technical Notes & Information — supporting documentation
Products that meet NMRA requirements may carry the NMRA Conformance/Inspection Seal.