Filter Retaining Masks for ZWO EFW 8 × 31 mm (SKU: ZWO EFW-8-MASKS) are a set of 10 masks designed to secure round 31 mm unmounted filters in ZWO electronic filter wheels. The masks hold the filters around their edges, leaving a clear aperture of 28 mm.

The set is compatible with the earlier ZWO EFW 8 × 1.25" / 31 mm eight-position filter wheel and the EFW-5x1.25-25 and EFW-8x1.25-25 models introduced in 2025. Each mask has three mounting holes and attaches to the filter wheel carousel using the included M2 × 4 screws. The set allows worn or missing retaining components to be replaced.

Key features

• secures round 31 mm unmounted filters
• compatible with the earlier ZWO EFW 8 × 1.25" / 31 mm eight-position filter wheel
• also compatible with the 2025 EFW-5x1.25-25 and EFW-8x1.25-25 models
• 28 mm clear aperture and three mounting points on each mask
• set of 10 masks with mounting screws

Included items

• ZWO EFW-8-MASKS filter retaining masks – 10 pieces
• M2 × 4 Phillips flat-head screws – 1 set

Technical specifications

• manufacturer: ZWO
• model designation: EFW-8-MASKS
• compatible filter wheels: ZWO EFW-8x1.25, EFW-5x1.25-25, EFW-8x1.25-25
• supported filters: round, 31 mm, unmounted
• mask clear aperture: 28 mm
• number of mounting holes per mask: 3
• mounting hole diameter: 2.2 mm
• mounting screws: M2 × 4
• mask colour: black
• number of masks included: 10