The Swarovski BOOSTER is easy to assemble and fits for all EL and SLC models (except SLC 8x30 WB). Simply unscrew one of the two twist-in eyecups and screw on the booster, which transforms for example a SLC 15x56 WB to a monocular telescope with 30x magnification! This awesome package includes a soft neoprene case with belt loop.