Too heavy for helium

Bought for a balloon release for my dad and grandpa on father's day. Very heavy material which I thought would mean they were durable, but actually it's just too heavy to float. We checked the helium we bought separately on a standard latex balloon and it flew fine so it was definitely these balloons unfortunately. We had to break a seal in order to inflate them at all, idk if that's standard but seemed strange to me. Return started.

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