Dry hopping in mesh bag?????

I am wanting to dry hop my current beer that is in my primary. I am going to use my secondary to do this, and just rack on top of the hops. I am planning on using whole hops in a mesh bag but I would like to weigh the bag down some.
What does everyone use for weight when they do this?
I have tried searching for a type of weight to use but have not really found anything, I did see that some people say the hops will fall within the first couple days though, but I would rather weigh them down instead. I was thinking of using some little ceramic balls that my wife has to weigh down pie crust when baking, any thoughts on this?

Thanks in advance. Craig

I have seen people use everything from SS bolts, glass marbles even river rocks... I prefer the marbles, but I could be wrong.

I've never used a weight for mine. I just toss the muslin bag in and let it float

Thanks for the replies, you got my brain working with the marble comment. I dont have any marbles though. So thinking outside the box since I am racking into a glass carboy, any glass would not hurt my beer providing that it is sanitized. What about using a skinny shot glass in the mesh bag. The only drawback I can see in this is paint on the side of the glass, I really dont think it would hurt though, I mean it is safe in the dishwasher, right?

I use the stainless ball bearing goomers from the keg spears I removed, but I know a lot of people use shootin' marbles. - Dwain