yes, the filter size is 55mm and your Nikon D3400 AFP-DX 18-55mm lens size is 55mm, so the filte can fit your camere 

hello Nikon 18-55mm f/3.5-5.6G lens size is 55mm, so the filter can fit it 

For camera with telephoto zoom lens, you need to buy a tripod mount ring additionally or telephoto lens bracket for better balance) 

The adapter will mount the lens and you will be able to use it manually. However, my copy of the adapter does not allow the lens to be fully mounted all the way until it clicks into place. It doesn't quite make it, but it's still very solidly mounted. Also, the manual aperture linkage doesn't work properly (on my copy, at least) so exposure is controlled only by shutter speed and/or ISO. You will be able to manually focus and zoom the lens but no VR, of course. It will be a frustrating experience. Instead, get a 14-140 Panasonic zoom if you can afford it! 

Hi, we checked the Sony a6600 18-135mm lens seems 55mm, if you like this filter, please reconfirm the lens size, the 55mm lens need to order 55mm size filter,thanks.