an improved blow molded plastic container having generally rounded sidewalls that are adapted for hot - fill applications has two adjacent sides and two pairs of controlled deflection panels , each pair reacting to vacuum pressure at differing rates of movement , whereby one pair inverts under vacuum pressure and the other pair remains available for increased squeezability or extreme vacuum extraction . the opposing sidewalls are symmetric relative to vacuum panel and rib shape and placement . the ribs and controlled deflection panels cooperate to retain container shape upon filling and cooling and also improves bumper denting resistance , decreases vacuum pressure within the container , and increases light weight capability .