When this black guy was introduced at NAMM 2014 show, no body realized that expansion concept might be applicable in to a speaker cabinet soley for use with combo or any other guitar cabs such as 212 or 412. Extention or expansion? No body knows what it really teaches expansion in the tecnowledge of speaker csbinet simulations. But it really works when it comes to bring back your guitar sound not available with those traditional speker cabinets,rolling off signal strength in the venicity of 4-5K freq. levels. A highs and lows as was originslly generated in your guitar sound has indeed been retrieved by means of this real thing IRT-X. What a big progress in the domain of guitar sound amplification to those people working at a relatively limited budget. Two-way, stereo and 3-way configurations in your sound system has come true without bulky cabs and additional amplifier. Thanks to people at Laney in the UK!