Crutchfield split the things you need into two pieces(you need BOTH in order for your head unit AND vehicle warning chimes to work, no way around it).
Sonicelectronix combined both of them into whole piece. Sonic is a bit cheaper by a few bucks. You are looking at 60$+ on top of your head unit. Thats why the audiocontrol loc is a much more appetizing choice, it gives a strong preamp signal has all the outputs you need for amps and subs along with crossover functions. Just telling you now man, this sh*t about to get real expensive, car audio is a slippery spending slope.