This is a variant of the weekly, 5x5 SLR product created at the University of Texas’s Center for Space Research (CSR) which is released alongside the GRACE series: ftp://podaac.jpl.nasa.gov/allData/tellus/preview/L2/deg_5/CSR.Weekly.5x5.Gravity_Harmonics.txt. The version here is averaged monthly, rather than weekly, to make it more directly comparable to the monthly GRACE data. It contains an estimate of C61/S61 (but no other degree-6 harmonics) to avoid skewing the C­21 harmonic due to a lack of sufficient degrees of freedom during the creation of the SLR gravity product (Cheng and Ries, 2017). From January - November 1993, only four satellites were used in its creation (Starlette, Ajisai, and Lageos 1 and 2). After that point, Stella was added as well. Data exists through mid-2017. The layout of the files contains a header section followed by one line containing the date for the following lines, and then 22 lines of spherical harmonic data. The time lines are formatted as: IARC, MAXDEG, NP, IYEAR, IM, XMJD: IARC: the arc number (ie: month number) MAXDEG: spherical harmonic maximum degree/order of the field NP: number of coefficient pairs (Cnm & Snm) IYEAR: year IM: month XMJD: epoch of the arc at the first day in modified Julian date The data lines are formatted as: N, M, Cnm, Snm, Cnm-sigma, Snm-sigma: N: spherical harmonic degree M: spherical harmonic order Cnm: C coefficient Snm: S coefficient Cnm-sig: The formal errors of the C coefficient Snm-sig: The formal errors of the S coefficient