The Portuguese gag acts the same as a snaffle bit. Attaching the reins to the bottom ring creates more leverage making the bit ideal for maintaining control of your horse. When the reins are placed on the lower ring, poll pressure is increased and encourages the horse to lower the head.
The Elliptical Link Snaffle Bit has a rounded central piece and therefore gentler in the horses mouth. The elliptical mouth reduces pressure on the tongue and bars of the mouth as well as the palate. Elliptical mouths encourage a softer contact.