  Two magnetic braking models are implemented in MESA for use in the MIST
stellar model grids. Stars less than about 1.3 $M_{\odot}$ are observed to spin
down over time through interaction with their magnetized stellar winds (i.e.,
magnetic braking). This is the basis for gyrochronology, and fundamental to the
evolution of lower mass stars. The detailed physics behind magnetic braking are
uncertain, as are 1D stellar evolution models. Thus, we calibrate our models
and compare to data from open clusters. Each braking model tested here is
capable of reproducing the data, albeit with some important distinctions. The
Matt et al. (2015) prescription matches the slowly rotating stars observed in
open clusters, but tends to overestimate the presence of rapidly rotating
stars. The Garraffo et al. (2018) prescription often produces too much angular
momentum loss to accurately match the observed slow sequence for lower mass
stars, but reproduces the bimodal nature of slow and rapidly rotating stars
observed in open clusters fairly well. We find additional evidence that some
level of mass dependency may be missing in these braking models to match the
rotation periods observed in clusters older than 1 Gyr better.
