A cap seal and a doubly-sealing apparatus of a container such as a drum using the same, which execute a reliable sealing function of a cap part of the container such as the drum. The topical composition may additionally comprise, in the eutectic mixture, a third or fourth pharmaceutically acceptable component. Functions performed by the engine include biquad filtering and inverse discrete cosine transform including pre-multiplication, inverse Fast Fourier transform, and post-multiplication, which would otherwise be performed by the DSP. A brace for a body of a guitar includes a unitary structure adapted to mount to a soundboard of the guitar.