The 18" Sub-slab Injector SSI-4 is for application beneath concrete floor to reach the void areas below, or to treat through tile or wood flooring to reach voids and spaces beneath concrete flooring. The injection hole through the substrate is sealed with an expandable rubber gasket. Each Injector Kit has two directional tips (180 and 360 degrees). The tips have 2-gal / minute flow rate and check valve provides tip shut-off. The Sub-Slap Injector SSI-4 is 18-in high.