Some time ago there was a post (can;t find it now) about someone that fell into exactly the same trap as me, bought an Orbit irrigation timer from Amazon for much less than the local price just to discover in USA they use a special "Garden Hose Thread" for garden hoses. It is close to, but not the same as used by virtually every other country. To make it worse, the part number that Orbit uses for the product sold in the USA is exactly the same as in NZ. My temporary (now almost a year) solution is to use 2 washers to seal before the different pitch thread interferes.
I have tracked down an apparently suitable adapter that could be used for connecting 19mm polypipe. I have not bought it yet, but pretty sure this is it. GHT is approximately 26mm diameter, the size in the listing refers to the hose size and you can also get ones for 16mm or 12mm hoses.
http://www.ebay.co.uk/itm/400818114319