This CQ 562 ladder line with 300 Ohm has a specification of 7 x 7 x 0.20, is black in colour, and is UV-resistant.
Maximum power handling is 1000 Watt.
The “windows” reduce the wind load area.
The flexible inner conductors (stranded steel copper plated) prevent destruction from wind gusts.
Some competitors sell ladder lines manufactured differently to ours. Their conductors are not stranded, they are rigid. Those conductors can be easily broken by wind gusts.