REL Tzero MKIII Powered Subwoofer for Small Room The Tzero MKIII packs the signature REL sound into a compact, affordable subwoofer that enriches smaller systems with powerful, natural bass. Built with a new aluminum cone for strength and punch, plus a high-efficiency Class D amp, it delivers deep bass in limited spaces like apartments or studies. Design Precision With high gloss black or white lacquer, the Tzero MKIII also includes REL†s renowned High-Level Input, separate .1/LFE input, and a fast 8ms filter.