Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Defective design: bad o-ring support.

It is a defective design. The metal body where the o-ring resides does not provide a proper surface for the o- ring. Instead the o-ring resides on the male threads for the screw cap. The threads cut into the soft rubber o-ring and the o-ring can not sit straight.You can not see the threads under the o-ring in the sellers photo, so I am letting you know. The threads go all the way to the hilt.When you screw on the cap it does not seal properly to the o-ring and further presses and scrapes the o-ring on the sharp threads. This cuts the o-ring with use.When I received the oiler I was amazed such an obvious defect was not addressed in the design. It is rare that I am unhappy with an Amazon order.