Frequently Asked Questions How tightly should I screw the ring on my Philips Avent Natural glass bottle? Find out how to best fit the ring on your Philips Avent Natural glass bottle. Assure the best fit The design of the bottle neck is such that there should be a gap (see picture below) between the glass bottle body and the plastic screw ring. If you feel some resistance when assembling the screw ring to the bottle, please do not screw any further. The bottle is screwed tightly enough. Please do not overtighten the screw ring. Overtightening the screw ring could damage the plastic screw thread.