Where's that gif of the Guinness guys yelling "Brilliant!"?that is for reemay cloth to lay over the plants to keep cabbage moths from laying eggs.
I use to use old thread bare white sheets to cover the plants which would get too heavy in the rain (reemay doesn't as much but will still weigh the plant down especially when they are younger.
The wire is 6x6in concrete reinforcement wire three feet wide in an arc.
I will be putting two together to make a taller 'tunnel' to accommodate the larger plants.
I have used it covered with plastic like a poly tunnel to get a jump on the season but the plastic doesn't last long rubbing against the rusty wire
hope that helps !