请教一句话的结构

this portion also comprises an annular collar 43 transversely connected to portion 41
as well as an annular lip 44 connected to the opposite peripheral end of portion 42 to that joinde to portion 41.

请教这句话的语法结构，“that”指代什么？

请教高手，这句话怎么翻译好？

不胜感激！！！

“connected to the opposite peripheral end of portion 42 to that joined to
portion 41”

可以改成：

“connected to the peripheral end of portion 42  opposite  to that joined to
portion 41”

that 指代与文中的“the peripheral end of portion 42  ”相对的portion 42 另一端
(end)。

多谢！

但是还是没怎么看明白

这个结构是怎么看出来的？

这句话翻成中文怎么说？

不胜感激！