The filter thread size of Panasonic Lumix G Vario 100-300mm F4-5.6 II Power OIS is 67mm.
Below are links to the filters that we recommend you to consider for your Panasonic 100-300mm F4-5.6 II OIS:
Read our detailed Panasonic Lumix G Vario 100-300mm F4-5.6 II Power OIS Review