Ahhh....yung "din" eh parang sleeve or receptacle yun na pwede mung ilagay then hugutin yung HU mo. Dati kasi (70's - late 80's) eh shafted yung HUs ng mga tsikot. Yung shafted HUs, yung receiver mismo eh kinakabit galing sa ilalim ng dash. Tapos, sine-secure in-place with a face plate. Medyo mahirap gawin so yung mga HU manufactures dediced to adapt the 'din' design.

Normally, ang size ng single din eh 2" (H)x 7"(W). Yung double din na tinatawag eh i-doble mo lang yung height, pero same ang width.

A good example of a double-din HU eh yung HU nung nasa Altis 1.8. Normally, yung mga double-din HUs eh may CD na, may 16-track cassette player pa. Yung ibang double din, walang cassette player pero hiwalay yung equa or DSP.