Manufactured From Eco Friendly Recyclable Glass, These Are Dishwasher Safe Products. The High Quality Metal Drinking Spout And Cap Unit Ensures The Bottles Are Chew Proof, And The Industry Famous (And, Of Course, Classic Originally Designed) Double Ball Bearing Method Of Water Retention / Release Guarantees A Leak Free Bottle. A Fun Looking Water Level Indicator Allows You To See At A Glance Whether It Needs Refilling And A Capacity Graduation On The Bottle Back Is Useful For Specific Filling Level Requirements. The Bottle Attaches To A Cage At Two Separate Points Through A Sturdy Spring Clip And Hook Bracket.