Size of medicine balls

Just wondering what size of medicine balls people would one give to a females between 130-150lbs?

also myself i’m about 180lbs i use a 12lbs ball, should i use a heavier ball?

It depends on their strength level and what you are using the ball for. I sometimes use a 8lb ball, and sometimes a 17lb ball (I am at 201lbs). The 17lber is sometimes too heavy for certain explosive throwing movements, but it is good for steady paced abdominal work.

i was refering to exercises on the DVD. the explosive and lower intensity partener work.