A generic-type magnifier for airsoft scopes reviewed by Airsoft Mike... "Here I get my hands on an awesome bit of kit! The unbranded 4x Magnifier that compliments your EoTech type holosights and red dot sights! It magnifies your target and includes a Flip To Side (FTS) mount for that added tacticoolness!

This particular model retails between £25 to £32 on ebay, depending who you buy it from. They are generally cheaper when bought direct from China, but not that much more expensive if purchased from a UK seller. Naturally if you live in America, you can get it even cheaper."