Yup, some bikes were just made for those o-rings. I used one too, but it requires a tight fit between the bar-end weight and the throttle.
It's a Vista Cruise in the picture. The "Honda" model (Model # MCVICO), more specifically. There is a "Yamaha" model, but I find this one easier to adapt. Adapt being the key word here, these were designed when motorcycles had semi-open throttle setups with the cables coming out of the bottom, right next to the throttle, not everything hidden under the the housing, so some modification is required. Also, most newer throttle tubes have ridges that go all the way to the end of the grip, those reduce the surface area your throttle lock has to work with, so I sanded the ridges down at the end of the tube to get one smooth surface all around the circumference.
On the Versys I used a self-tapping screw straight into the back of the cable/switch housing. I can't find a picture right now (and the bike is 1000 miles away), but it uses the notched tab in this picture to secure the lock:
On the V-Strom I used safety wire (I think you guys call it locking wire), to fix that tab, as there was no room in the housing to tap at the angle I wanted. Both work very well after you adjust the tension on the adjuster screw (and like all things mechanical, it vibrates loose, despite being spring loaded, so it requires periodic adjustment to keep in the sweet spot).
I had an NEP on the DL1K. I like the Vista design better, but both work well.