For 2018 the big news was the introduction of the option of a switchable clutch on microSHIFT's higher end mountain bike derailleurs. There were nine new mountain bike derailleurs:
microSHIFT XCD (M785L) - a top end model with a clutch, that can be engaged or disengaged
microSHIFT XLE 11 (M625L) - a mid range model with a clutch, that can be engaged or disengaged
microSHIFT Mezzo (M36L) - a low end model with a long cage
microSHIFT Mezzo (M36S) - a low end model with a short cage
microSHIFT M26L - an even lower end model with a long cage
microSHIFT M26S - an even lower end model with a short cage
microSHIFT M21L - a very basic model with a long cage
microSHIFT M21S - a very basic model with a short cage
microSHIFT M21SS - a very basic model with a very short cage