I converted CharGriller Duo to Natural Gas (NG). Ordered circuit board drill bits: Xuchuan circuit board bits. Used this website to convert from millimeters to the correct Wire Bit size - www.riogrande.com. Cross references to this chart to estimate BTUs - www.joppaglass.com. Did not measure water column (WC). Used old NG grill orifice size by seeing which drill bit fit. Through trial and error, I increased the bit size until I had a good flame and the burners fully lit.