Hi, you can attach center-pinch lens cap on this filter , except the ND1000 filter , the CPL, UV and magnetic adapter ring can attach lens cap. 

Hello! If you use the magnetic UV filter separately, or use the magnetic adapter ring together with the CPL filter, you can use a normal lens hood on it. Does not require a larger thread. If you use the magnetic adapter ring together with the ND1000 filter, you cannot use another lens hood on it. 

1. The UV filter can be used alone. ND and CPL need a matching magnetic adapter ring, because the camera lens itself is not magnetic and cannot be directly attracted to ND and CPL 

It is a normal phenomenon if you want to use ND filters together or ND filter with other filter, like ND2+ND4,ND4+ND8,ND2+ND8 or ND2+4+8,ND filter+UV, the photo effect will become to light pink color, you could set "white balance" as "AUTO" to improve it, but will not be completely disappeared. 

The adapter clicks on the lens. It has a small dark gray colored lever (not the white plastic tab to change aperture), level to the outer edge of the bottom ring accessible when removed from the camera, grab the whole adapter with your left hand and push the lever in with your thumb, and while pushing, rotate the lens with your right hand to remove it. You need to push in that lever to unlock the lens.