A cap for holding a powder to be mixed with a fluid in a bottle has a product cap with a reservoir. The product cap has a top wall and a side wall. The product cap has a number of inner protrusions on the side wall and a number of outer protrusions on the side wall. A cylindrical safety gate has a number of grooves. The inner protrusions of the product cap mate with the grooves of the safety gate. The cylindrical safety gate has a gate and an aperture at an end of the cylindrical safety gate. A bottle cap with a cylindrical body has a threaded end and a gate end. The gate end has a number of grooves that mate with the outer protrusions. The bottle cap has a gate and an aperture between the threaded end and the gate end.