1. 含挡圈端部加强型(浮筒端/管汇端）
End Reinforced with Float Collars (i.e. under Buoy / off PLEM)
2. 含挡圈主线型
Main Line with Float Collars
3. 无挡圈端部加强型(浮筒端/管汇端）
End Reinforced without Float Collars (i.e. under Buoy / off PLEM)
4. 无挡圈主线型
Main Line without Float Collars
