The Butler Creek Multi-Flex Flip-Open Eyepiece Scope Cover (Size 16–17–18) protects rifle scope ocular lenses from environmental contamination while allowing rapid, silent optical access. Designed with a flexible elastomeric sleeve, this slip-on cover fits ocular bell diameters ranging from 1.660" to 1.700" (42.3 mm to 43.2 mm), accommodating minor dimensional variances across three standard scope sizes. The spring-loaded lid opens instantly with a thumb press on the ergonomic release button, clearing the optical path entirely. An internal semi-O-ring creates an airtight and watertight seal to exclude moisture, dust, and fine debris during field carry, transport, and active shooting.

Key Features

• Multi-Flex Elastomeric Collar: Provides flexible stretch to securely fit ocular bell diameters between 42.3 mm and 43.2 mm (1.660" to 1.700"), covering standard sizes 16, 17, and 18 with a single slip-on sleeve.
• Instant Spring-Loaded Deployment: Push-button thumb actuator silently releases the spring-assisted cap to swing fully clear of the optical field of view.
• Weatherproof Environmental Seal: Internal semi-O-ring creates a watertight and airtight barrier against rain, snow, fine red dirt, and bull dust.
• All-Weather Reliability: Engineered to function consistently across an operating temperature range of -40°C to 49°C (-40°F to 120°F) without binding, cracking, or losing spring tension.
• Durable Construction: Built with a rugged polymer body, flexible rubberized collar, and a steel hinge spring, weighing approximately 50 g to 63 g (0.11 lbs to 0.14 lbs).

Specifications

• Model Number: BC21618 (21618)
• Category: Flip-open rifle scope eyepiece cover
• Fit Range (Eyepiece Bell Diameter): 42.3 mm to 43.2 mm (1.660" to 1.700")
• Attachment Type: Slip-on flexible collar
• Operating Temperature Range: -40°C to 49°C (-40°F to 120°F)
• Materials: Polymer body, rubberized collar, steel spring
• Finish: Matte Black with yellow push-button release
• Weight: Approximately 50 g to 63 g (0.11 lbs to 0.14 lbs)
• Power Requirements: None (mechanical)

Who is the Butler Creek Multiflex Flip Open 16-17 Eyepiece for?

• Hunters stalking or glassing in dusty and wet environments — relies on the internal semi-O-ring seal and an operating envelope of -40°C to 49°C (-40°F to 120°F) to keep fine bull dust and moisture off ocular lenses on rifle scope eyepieces measuring 42.3 mm to 43.2 mm.
• Tactical shooters requiring rapid target acquisition — utilises the push-button spring release on this flip-open eyepiece cover to silently clear optics seated in the 1.660" to 1.700" collar with a single thumb movement.

Less suitable for: Rifle scopes with ocular bell diameters narrower than 1.660" (42.3 mm) or wider than 1.700" (43.2 mm), which cause loose retention, compromised seals, or collar tearing; these optics require smaller or larger dedicated Multi-Flex scope covers tailored to their specific bell measurements.