The Fiber Optic Splice Closure 2178 family includes seven distinct models – XSB, XLB, S, SL, LS, LL and XL – in flame-retardant and non-flame-retardant versions with flexibility built-in for growing networks. Providing excellent system. Describes the 3M™ 2178-L/S Series Fiber Optic Splice Cases and their applications. Details maximum cable diameter, closure dimensions, and splice tray capacities. 3M 2178-S, Fibergate, Black, Multi-mode.