The Lochcarron price list that I have says that Reiver is 10 oz, and I just took what they said about their own tartan at face value.

Like everything that Locharron weaves, Reiver is beautiful tartan. I used it to make a couple of kilts several years ago, though, and I find it on the light side for a man's kilt. If it were the only material available in a particular tartan, I would use it again if the customer didn't want the expense of a custom weave. But I prefer something heavier for a man's kilt. And, if I were making a kilt for a dancer, I'd choose Dalgliesh's 11-12 oz tartan over Reiver. It's just enough heavier to resist wrinkles.

Well, that's my humble opinion, anyway.

Barb