hollow-shell welded and fiberglass float

[Redrum-wt]

это как? пустотелый сварной и оптоволоконный поплавки?

контекста почти нет,

it says only that:

these instructions apply to systems that use a hollow-shell biberglass (or welded) float that is bla-bla in diameter and heights.

[Redrum-wt]

anybody help me can? plees? ;)

[Enote]

пустотелый стеклопластиковый (или сварной)

[Redrum-wt]

thanks)))