Although it is also in the comments of other people, it is convenient to put without a gap because it is a square type. I'm glad that you improve, I think that there is no need to worry about disappearing when the injection nozzle and cap are connected to the handle.
Previously I put detergent in a 4 L plastic bottle (cylindrical type) and kept it, but I bought it again. Because it is a square shape it fits well and it is lower than 4L PET bottle. I do not roll even if I lie down, because the handle does not jump out, it will not get in the way. Usability is better when you pull the handle sideways rather than the top.