Century is a company based in Oklahoma that create all types of martial arts as well as boxing supplies, among which is the heavy bag used at the gym where I do routines on thrice weekly.  For 30 years, the company has been making its original Wavemaster bag.  It is a portable bag made up of high impact foam with vinyl as a covering.  It has a flexible base that is round made from polyethylene that is durable and either sand or water can be used to fill it up.  There is a choice of three colors:  red, blue or black.  Mine is blue.  It is an adjustable bag from 52” to 70” in height.  The weight is roughly around 270 pounds when its base is filled fully.  Among its great features include the flexibility of being rolled along the rounded base to even when it’s filled for easy transport to another location.