Parameter Item	Specification Data
Material	High-strength aluminum alloy
Surface Finish	Matte black anti-reflection anodizing coating
Standard Sizes (Male-Female Same Diameter)	25-25mm, 25.5-25.5mm, 27-27mm, 28-28mm, 30-30mm, 30.5-30.5mm
Thread Structure	One end external male thread, the other end internal female thread, both ends share identical thread diameter
Core Function	Extend optical assembly length, stack multiple filters/lenses, act as lens hood spacer
Construction Feature	Full metal integrated machining, high concentricity, low distortion for optical imaging systems

Product Application Scenarios
1. Machine vision lens assemblies: increase distance between lens and filter to avoid vignetting
2. Stack multiple optical filters (narrow bandpass filter, CPL polarizer) simultaneously on a single lens
3. Spacer ring for custom lens hood, block stray ambient light
4. Laboratory optical experimental setups, precise optical path length adjustment
5. Astronomical shooting equipment, filter stacking extension accessories

✅ Premium CNC machined aluminum alloy, lightweight yet rigid, resistant to deformation after long-term use
✅ Matte black anti-glare coating eliminates internal light reflection to prevent imaging flare
✅ Same-diameter male-female double thread design, seamless stacking of multiple optical accessories
✅ Multiple mainstream industrial standard thread sizes compatible with vision lenses and optical filters
✅ High concentricity machining ensures no image shift or distortion after installation
✅ Multi-purpose design: works as extension spacer, stacking ring, or lens hood adapter
✅ Easy screw-on installation, stable locking without loosening during equipment vibration
✅ Widely matched with narrow band filters, CPL polarizers, industrial cameras and astronomical shooting lenses
✅ Custom thickness and other thread diameter options available upon customer consultation