best magento layered navigation extension

[ShaileshThapa]

Hi, I need a best free or paid  layered navigation extension which has the following qualities :- 

1) layered navigation links are search engine friendly .

2)   we  can use the price filter for the grouped products.

3)  we can use this extension in our development website after buying it .

4)  we can select multiple check boxes in layered navigation .

5)  the paging links are search engine friendly.

Can any one give the web-links so that i can check and get the links from there.

Thanks 

[Amasty]

Hi @ShaileshThapa

you can check out our Improved Layered Navigation extension

This is our best seller with all the features you've mentioned and many more.