Handmade pickup for double bass. This is the type that is placed under the bridge on the low-string side. It's a Realist-type pickup, a classic. The sound is the same as the ones I've made so far, but this model uses a jack with a locking function. When you lower the red claw, the lock is released and the plug can be pulled out. This might help to avoid the situation where you get excited on stage, step on the cable, the plug comes out, there's silence, and then you frantically plug it back in, only to get a lot of noise. Also, when using cables from various manufacturers, the jack tends to loosen, but I think this can be somewhat reduced, so if you put it on shared basses, etc., it might increase durability. On the other hand, it generally clicks in firmly, so it's stable, but in the fourth photo, although the plugs look similar, (bottom photo) the Amphenol one doesn't lock as well, and probably the Soundhouse original... (top photo) the L-shaped phone jack locks strongly. The locking strength may vary depending on the cable you use. Since the R-shaped clip becomes too large, it will be attached to the tailpiece with a cable tie. A protrusion made of heat shrink tubing is wrapped around the jack to act as a stopper for insertion and removal.