Spinning reel spool made lightweight overall, while maintaining the strength of its bobbin trunk and skirt. An application of this method and apparatus to personal computers is also disclosed. Two pumps with two separate hydraulic control systems are used with a side loading refuse vehicle. The tile also includes a first formation at or adjacent one side edge, and a second formation at or adjacent an opposite side edge that, in use, interlocks with a corresponding said first formation of an adjacent roof tile. The decompressing unit receives the compressed gain signals and then decompresses the compressed gain signals to obtain a plurality of gain signals.