Daldorado DPAS-12-BO 12" Bone Parallel Straight Grate Daldorado’s SILENTFlow™ commercial pool grating system is the most superior evolution in parallel grating. All grating features the highest flow rate with an unprecedented 40% open area and whisper quiet noise reduction. Daldorado’s SILENTFlow™ parallel grating has been engineered to make installation so easy you will want to install it on all your pools. Installed correctly by hand to Daldorado-Installation-Instructions it will minimize expansion issues.