SangP:Halcyon's wings are rather expensive but there are plenty of alternatives that are just as good or better like, Oxycheq Signature series, Deep Sea Supply, Golem Gear just to name a few.
There are some wings where the inner bladder is completely urethane, which makes patching easier.
Best regards,
SangP
Actually, the Golem wings have the inner bladder made out of polyurethane coated 650 denier Cordura (same stuff outer shells on most other wings are made of), it is almost impossible to puncture and during CE testing it was pressurized to 180bar (2600PSI) without problems.