This sale is for a pair (2) of brand new reproduction 2308 / L91 accoustic lenses. The lens is reproduced from a set of original JBL, but the tabs for mount screws has been removed for aesthetics reasons, as most mount with velcro any way. They are made of plastic. The orignal lenses are prone to break due to age, and original are are almost gone and prices for good used examples have sky rocketed. Other reproduction exists but are still very expensive. This set lenses are manufactured in accurate measurement and are very identical in appearance to the original lenses offered by JBL except for the fact that the ugly mount tabs has been removed. All you need to install are velcro tape strips or double sided tape. The lenses will fit JBL 4320, 4331, 4333, 4340, 4341, 4343, 4344, 4345, 4350 and 4355 studio monitor series. They also fit for C50SM, C51, C60, C61, olympus, L200, L200B, L300, L300A and many other builds. Keywords: JBL 2308, JBL2308, JBL L91, JBL L91 Lens, JBL Lenses.