Double Lpg Regulator

we are looking to purchase regulary double lpg regulators similar to model 524as.
technical data :
- capacity : 4 kg/hr.
- outlet pressure : 30 mbar.
- inlet connector : 4" npt ( f).
- outlet connector : 3/8" npt (f).
the item has to be certified
please source for such a device and quote the price for 10000 pcs.
best regards,