Bostik QuartzLock2 Grout 370 Raincloud Gray 18 lbs. by Bostik QuartzLock2 Grout Pre-mixed sanded grout; Easy to install for DIY or contractor use New 3 Day RapidCure for Intermittent Water Exposure; 7 Day RapidCure for continuous water exposure Chemical and mildew resistant; Contains Bostik's Blockade antimicrobial protection Flexible properties; Resistant to cracks and shrinkage Offers limitless design possibilities