New Manuka Honey Mgo 500+ 250g Manuka Honey MGO 500 The MGO content is given in mg/kg. MGO stands for methylglyoxal, the main ingredient in manuka. The UMF value is also determined for this honey - the higher this is, the richer the honey is. The American Low Value Shipment Regulatory Modernization Act is active since March 2016 and increases the duty and tax free value of goods American citiziens could import from other countries by mail from $200 to $800 as well as no formal customs procedures are required. The American Low Value Shipment Regulatory Modernization Act is active since March 2016 and increases the duty and tax free value of goods American citiziens could import from other countries by mail from $200 to $800 as well as no formal customs procedures are required