It's a type of fastener consisting of a hexagon head and a screw (cylinder with full thread), which needs to be matched with a nut to fasten and connect two parts with through holes.
Acid Activated Bleaching Clay is a Food Grade Calcium Bentonite Clay Powder. It is Natural Bleaching Earth and can be used for decolorizing and refining oils (its like vegetable oils, animal fats, mineral oils) without chemical treatment and also for Vege