What is the use of the speedbag and double end bag?

I just want to ask this questions. What aspect do they improve like speed or accuracy or power or etc.


and oh. can you also include what the heavybag does? is it for power?

speed back conditions your tris and shoulders and improves coordination and timing. double end bag is for timing and slipping with combinations because if you throw a straight and not slip you get hit in the face when it comes back. heavy back just gives you a somewhat stationary target to get a feel of distance and how it feels when you hit a target. you can work angles on the bag too as it sways. shuffle step when it sways towards you and such.

speed, conditioning, and in the case of the d-e bag, reflexes.