Choosing timber for trussed roof diagonal bracing

[lasix]

I've decided to fit diagonal bracing in my trussed roof (survey mentioned it would be worth considering). I was looking online to buy the required timber. I've come accross the following two options:

https://www.travisperkins.co.uk/tre...ODtctzuzY9F4dk_qloRoCwhAQAvD_BwE&gclsrc=aw.ds

RFP 25 x 100 SAWN TREATED RESAWN EX LARGER PER M FSC MIX 70% SA-COC-002262 - 22-25mm - Huws Gray Ltd

Sawn treated timber, ideal for all exterior structural and garden projects

www.huwsgray.co.uk

Price-wise, there's quite a bit of difference... what's the actual difference between the two? If they are both fine I'd go for the second one as both timber and delivery cost WAY less! Any thoughts?
What does "ex larger per m fsc mix" mean? Is resawn timber suitable for this?

 

[^woody^]

Any 4x1 in lengths short enough to get through the hatch and around the trusses - sometimes about 2m or so, so allow for lots of overlaps.

Resawn is just rough sawn - cut down from larger sections "ex larger ...."

 

[lasix]

Any 4x1 in lengths short enough to get through the hatch and around the trusses - sometimes about 2m or so, so allow for lots of overlaps.

Resawn is just rough sawn - cut down from larger sections "ex larger ...."

So i guess the cheap option should be fine

 

[scbk]

What does "ex larger per m fsc mix" mean? Is resawn timber suitable for this?

"per m" means it's priced per metre, so a 3.6m would cost you £7.06 or whatever

Travis perkins tends to be quite pricey, unless you manage to get a good discount

"fsc mix 70%" relates to the source of the logs
"FSC Mixed - Any product certified as an FSC Mix must contain an absolute minimum of 70% FSC certified wood. The remaining volume(up to 30%) can from controlled sources, where an in-depth due diligence assessment has to be done."