We have two staffies, both girls so they are quite small weighing in at 19kg and 17kg respectivly.
This is probably slightly too big for our Staffie cross (labrador) but we havent had any problems with her slipping out due to the quality and width of the leather. Her old harness was definately too small being one of the cheaper nylon types and it just doesnt compare with this new harness, she actually walks prouder now she has a smart harness like her sister (and hers looks much better than her sisters that cost double the price of this one).
Its probably a bit too soon to rate the product having only received it 3 days ago, but we are very happy with it so far and will add an updated review after a few more weeks wear and tear.
As for the seller Doggy Trends, I ordered on Sunday and received the item on Tuesday despite going for their standard delivery service. Well packaged but not over packaged for those that are eco friendly *****