Bar End Weights

[Dead Eye]

For some reason, bar end weights just completely befuddle me  :\

I have just taken delivery of and fitted a set of nice new Renthal 758's but I need some bar end weights as they buzz like mad - my existing bars were just as bad and the buzzing has nothing to do with the Renthals

So, they are currently untouched. What do I do oh wise foccers and what do I buy...

I spotted these on eBay but they seem kinda expensive but are marked as for Renthal bars. Now, how are they fitted? Do these come with some sort of thing I put inside the bar or is that unnecessary in this case? Do I need to reuse whatever is inside by old bars?

At the end of the day, I don't want to buy something that ends up being useless and won't fit