For reference a bladder could also be a pillow tank but a bladder may or may not be self supporting. The ability of the pillow tank with it's self supporting layout retains about 70% of what a rectangle would. IPI has labored with tank factories for approximately two a long https://www.facebook.com/permalink.php?story_fbid=pfbid0yWuG7uBtsSTEXQ7jVxdE5yUsm8A5NPXd9FZj4jkpj22UU3fPnx2aG2nhR7AW23Zgl&id=61560512640678&__cft__[0]=AZWHEpHK2BqDPhPZsi2GJ1d_ln7tOIGeqp8dhxi0q7QBkdrBQ3dWaEMZn7xNC4PON5D1Vgh1dQGgpPXjJapDFS7QpvTLAyU-4-LX2IBpFfwOjhs6UkrhSAh2J4BQv7-BBug6zLhxJxFcGid6wTvBqUunAdCKUwgpbUU1E2xix3e39lk12RHtLRWR-hD5Dez3pas_eaGvAO7uXmXjmMZs2YGh&__tn__=%2CO%2CP-R