BARWALT Hollow Leave-In Tile Spacers are the first industry approved spacer to be left in. They act like rubber spacers but are hollow, which allows them to be filled with grout becoming an integral part of the joint. This unique feature eliminates the spacer removal step, allowing installers to grout earlier and save time. These spacers can compress up to 10% to allow for variances in tiles. They are longer than regular spacers to work with radius corner tiles. Choose between traditional + or T spacer styles in a wide assortment of sizes and quantities.