DISCLAIMER: All butane extractions should be done outside only, preferably on a breezy day, in an area away from anything that can create a spark which could cause an explosion during your extraction process. Be smart, stay safe.
I picked up one of these nifty little oil extraction units. I thought I'd post a review, especially since the first time I made BHO was with this rig.
The tube spans 11 inches, including the attachments and holds approximately 12 grams of bud matter (broken up, but not ground). I'm sure you could pack a little more in there, but not much unless you're using ground plant matter.
Both ends have 18mm glass on glass attachments making it easy to get all of that tightly packed plant matter out after your extraction. A keck clip for both ends was included with the the tube.
Rather then attaching a filter to the outside of the glass, a small piece of coffee filter can be placed in the end of the tube.
EDIT: This isn't necessary if you're using whole nugs.
As with any type of material, when doing a butane extraction the tube will freeze, so make sure to hold onto the tube with an oven mit.
Pros: A double sided glass on glass tube makes it easy to pack with nug, while also making sure there are no large air pockets anywhere inside the tube. It also makes it easy to get all of your plant material out after the extraction, not to mention it looks pretty damn cool packed tight with dank .
Cons: The downside of using a straight glass tube that uses 18mm fittings is it limits the amount of bud that you can cram in an 10 inch tube. This same design with 29mm attachments would be the shiz, but I'm sure would also cost a bit more as well.
I'm well aware that there are multiple ways to make your own extraction tube rather then dropping $50-$60 on one of these or an okief tube. I bought this partially out of laziness, and partly because I was curious. I couldn't seem to find any good reviews of glass on glass BHO tubes, and didn't feel like waiting for 2-3 weeks for an okief tube.
And I think most of you know what comes next...