Optia Light Sleeves can be used for two main purposes: to attach a glow stick/fishing light to your rigging, and to act as protection for your rod guides when winding in too far i.e. when using wind-on leaders. Available in Clear or Lumo colours, 50mm or 80mm long. Each packet contains 10 sleeves. Dimensions: The 50mm Optia Light Sleeves have a 4.5mm inner diameter section that's 20mm long tapering to a 2mm inner diameter section that's 25mm long. The 80mm Optia Light Sleeves have a 4.5mm inner diameter section that's 20mm long tapering to a 2mm inner diameter section that's 55mm long.