--- title: "How do I know which telephoto lens fits my M-Series glasses?" slug: "how-do-i-know-which-telephoto-lens-fits-my-m-series-glasses" updated: 2024-01-23T20:54:24Z published: 2024-01-23T20:54:24Z canonical: "support.vuzix.com/how-do-i-know-which-telephoto-lens-fits-my-m-series-glasses" --- > ## Documentation Index > Fetch the complete documentation index at: https://support.vuzix.com/llms.txt > Use this file to discover all available pages before exploring further. # How do I know which telephoto lens fits my M-Series glasses? The M300 has two possible eyepiece shapes. It is important to purchase the correct lens. Please reference this [diagram](https://d2iankuf53zudv.cloudfront.net/Content/Upload/PDFs/image_16_.png) for help identifying which version of this accessory will fit your device.