Lens material: pure optical glass Frame material: aluminum alloy Size: 1.25 inches (31.7mm) Thread: M28.6*0.6mm Net weight: 10g Note: M28 series thread is suitable for more than 90% of the 1.25-inch eyepieces in the market. If it is an eyepiece with M30 series thread, you can configure the adapter ring yourself. Tip: How to identify M28 series or M30 series – directly buy a sample of this model and test it. If the product cannot be rotated and the thread is small, then it is basically determined that the eyepiece is M30 thread. The eyepieces that support the connection of the filter currently in the market have only two thread specifications: M28.6*0.6mm and M30*1mm, which are industry standards. If it is another type, it may be special or does not support connecting filters. Q&A Q1: Can M28.5*0.6mm thread be used? A: Yes, it is the same! Q2: Can M28.5*0.75mm thread be used? A: Basically yes, but it cannot be fully rotated. It can be rotated for 1 turn without affecting the use. This specification is produced by those unprofessional factories. Q3: Can M28*0.6mm thread be used? A: It needs to be tested. If it is a product of our company, it is the same! In the early days of the M28 series, we marked it with M28*0.6mm as an abbreviation. If it is from another company, the situation is not clear, and the customer needs to test it by himself. Q4: Can M30*1mm thread be used? A: No, please refer to the above information. 1 filter 1 plastic storage box