Tusco Products TRSQ12SS Square Saucer, 12-Inch, Sandstone Rotation Molded Plastic Extremely Durable; Use Indoor or Out Weather Resistant and UV Protected,Proudly Made in the USA outside dimensions  15 x 15.inside dimensions  12.5 x 12.5,Height  1.75,fits a 12 base pot This square saucer will fit our 18" Cosmo Square and 32" Cosmo Tall Square Planters