Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Nikon DK-21 Rubber Eyecup Nikon Digital SLR Cameras

Excellent item for my Nikon D-90. The cushioned eyecup is not a necessity to the any of the operations of the camera, more a comfort item. SInce it is replaceable with several different eye cup versions, I like to have a few spares in my bag when travelling in case one goes missing.