For reference a bladder is also a pillow tank but a bladder might or might not be self supporting. The capability of a pillow tank with it's self supporting design retains about 70% of what a rectangle would. IPI has worked with tank factories for nearly two a long time https://www.facebook.com/permalink.php?story_fbid=pfbid0PAN2rE3pmUDmr17Y5kK5YC4ZChVy7eYDsDVcTnDwn3uYUgyzQu9huYuDkcTDp4J4l&id=61560512640678&__cft__[0]=AZU3LsMlVucm8wlXVjCyt8BXgNphC84v0TVL3g2l6PAbx_buK7RIkVJ7V8qAug41eNyO_nNiv6ch6X8vh283TdfEzi14J3wvDV3TsXblHyas7mq_CXj01vQr4yT53e-JipO8yaTSoni2zzRJaxURTa0orVvUKc2bvNUUrCdePc47NflmrxDSvF4TjozggNcO8yAu5dBM6AeZ_SftWf-SlTxO&__tn__=%2CO%2CP-R