Astralpool Base drain for swimming pools for collective use UNI-EN 13451 515x515 structure in resin and fiberglass and plastic grid. Suitable for pool with liner or concrete. Optional hydrostatic valve. The minimum distance for the installation of the drains must be> 2 m for pools with a collective one and> 1 m for pools for residential use. Available in sizes 515x515 with a diameter of 140 mm or 200 mm.