i think 10 but hard to say. i only play with him 10 to 15 minutes at a time. i throw the ball for him and he retrieves it with no problem. i also hide his ball and ask him to find it. i hide his ball or tee shirts, my GF shoes or blouse and he goes and finds them and brings them to me or to her if she's playing with him. next i'm going to hide a set of keys and then a wallet. i teaching him to retrieve the wallet and keys because i'm going to teach him to pick them up if i'm walking down the street and drop them or in the house just send him to get them for me.