Features: 1. The diagonal is equipped with thick precision optical plane mirrors with an enhanced 99% reflective dielectric coating 2. Dielectric 1/10 lambda level substrate, optical path length 85.5mm 3. The snap on fixture can achieve ultra fast clamping action 5. The internal safety block can prevent collision with the mirror 6. Stainless steel compression ring (on diagonal and adapter) can prevent damage to the eyepiece Specifications: 1. Brand: SVBONY 2. Model: SV223 3. Size: 1.25 inches 4. Optical design: Mirror diagonal 5. Internal connection (lens side): thread M28.5x0.6 6. External Connection (Lens Side): Tube 1.25 inches 7. Internal connection (eyepiece side): clip 1.25 inches 8. Reflective surface: dielectric coating 9. Reflectance:>99% 10. Image direction: Up and down, left and right reversed 11. Optical length: approximately 85.5 millimeters 12. Clamping system: Clicklock 13. Deflection angle: 90 ° 14. Aperture: 25mm 15. Material: Metal 16. Mirror thickness: 11.5mm 17. Net weight: 249 grams/8.78 ounces The package includes: SV223 1.25 "90 degree zenith mirror 1 M4 screw 1PCS dust cap 1PCS dust plug