Excellent price for a Global whetstone. This one in particular will be sufficient for typical use, 240grit from blunt, and 1000 grit for finer edge sharpening.
Usually stones like these are ~$100
Good investment for your good cooking knives (i.e. Shuns, Tojiros, Globals, Miyabis, etc)
Guiderails can be found here
Seems to be a lot of demand on this product to Canberra, ACT. lol