The sis shaker bottle 700ml the best bottle to use for mixing drinks this bottle is specially made for sis with handy markings that are a key part of the easy mix system sis shaker bottle 700ml features a must for rego build and rego rapid due to the whey protein this bottle is specially made for sis with handy markings that are a key part of the easy mix system to use start by adding drink powder up to the appropriate level as marked on the bottle then part fill with water and sha