NRFI — no run first inning — is an MLB prop that pays if neither team scores in the top or bottom of the first inning. The opposite is YRFI ("yes run first inning"). NRFI rates depend heavily on starting-pitcher quality, lineup top-of-order strength, and park factors. The NRFI Center on LineTerminal tracks pitcher-by-pitcher first-inning rates.
NRFI (No Run First Inning)
A bet that no runs score in the first inning of an MLB game.