public boolean matches(InstrumentSpec otherSpec) {
		
		if(! (otherSpec instanceof GuitarSpec) ) {
			return false ;
		}
		GuitarSpec otherGuitarSpec = (GuitarSpec) otherSpec ;
		if(otherGuitarSpec.getNumStrings() != this.numStrings ) {
			return false ;
		}
		
		 return super.matches(otherGuitarSpec);
		
	}