Field Notes Heavy Duty started out as a limited edition product and I believe is now part of their lineup (these posts are quick and dirty ones, so google things if you’re interested. The point of this exercise is to write these without pausing to search for things). I didn’t use them at all at first, but lately they have become my scratchpad of choice. I have a pair currently in use, and I throw whatever I need to remember into them, plus little things that I need to work out, notes that I take during phone calls, etc. Things then get processed from there, or just torn off and chucked away. Aaron Draplin would approve.
These take pretty much any kind of pen that you can throw at them and are decent enough even with fountain pens.
Pro tip: feel free to ignore the ruling and use them landscape style. This goes for any portrait oriented writing pad.