Fits between literally any two sabertrio sabers and makes them look like a consistent staff. I've been using a dark one (non-weathered) to connect my Brushed Senza and Weathered Vahlken and it looks amazing. Doesnt disrupt the design at all. Also as already commented above you can adjust how the sabers are aligned with a Hex Key Adegan's provides the the coupler, so you're not at the mercy of your threading.
The sound venting also is really good, the sabers are still very loud unless you directly grab over every sound hole of course. If you have 2 or more Sabertrio sabers, definitely get one of these.