Definition: The throw angle of a rubber is whether the rubber tends to 'throw' the ball higher or lower when making the same stroke. Given the same return from your opponent, and the same stroke by you, a rubber that puts the ball in the net is considered to have a 'lower throw' than a rubber than puts the ball on the table. For the same circumstances, a rubber that puts the ball off the end of the table is considered to have a 'high throw'. You will sometimes hear players talk about 'degrees of throw' - basically a rubber than puts the ball low has a low degree of throw, and vice versa.
Generally, low throw rubbers have degrees of throw in the 30s, while 40-44 degrees of throw is roughly a medium throw rubber, and higher than 44 degrees of throw is typically considered a high throw rubber. These numbers are not exact, and may vary from manufacturer to manufacturer.
This throw angle is not an exact science (contrary to what you might think from reading on the various forums!), but more of a comparative feel between different rubbers. A rubber with a high throw is not better or worse than a rubber with a low throw, it is just different. Generally, low throw rubbers are considered to be easier to play with against topspin, while high throw rubbers are supposed to be able to lift backspin over the net more easily.
Also Known As: throw, degree of throw, hardness, degree of hardness
