@candyquilt-- A macadamia cracker does not necessarily need to be labeled for macadamias. Just make sure that the cracker is suitable for nuts of variety of sizes. Also make sure that it's very durable.
The first cracker I bought for macadamias broke after only a few weeks because it could not handle breaking such hard shells any longer. So make sure the cracker is heavy duty and can handle the hardest of shells.