Product description. ~ようになっている ('is set up so that X is possible,' literally 'has come to be such that X') is a compact way to describe an arranged or designed state. ツマミ ('knob, dial') is the standard word for a control knob. 光量 'amount of light' (kango). 演出する ('to produce, stage, direct') is borrowed from theater/film but extended to any creative 'production' — here, creating an ambiance. The second ~ようになってる is the contracted (~てる) form of the same construction.