The d-Rain Joint water filtration device from Bio-Microbics is designed to provide rainwater drainage along impervious surfaces such as concrete and asphalt. The joint is a permeable channel made from 6061-T6 aluminum and is installed like a standard expansion joint. The system provides a pathway for water drainage to an outlet or subsurface drain bed, avoiding stormwater damage. 913/422-0707; www.biomicrobics.com.