Related Clues:

• Lens
• Doc wears them
• Glasses
• Fireworks, air shows, glasses, etc.
• Visual aid
• Seeing things
• Monocle
• Viewing aid
• See through this to keep a watch on your tumbler
• I see I need only one like this
• One says with glee that that's a single see-through
• That'll give one monocular vision
• See 20
• See 12
• See 11