Today was a good day in many ways, but more so with the arrival of this.
It weighs in at perhaps 1 kg, contains a long object that moves end to end with a thud that appears dampened and so perhaps the ends are wrapped. When shaken I have the impression of a T shaped object with the centre piece being heavier than the bar - it sound like it is flopping up and down.
There are a number of marital aids I can image (since I have no experience of these I can only use my imagination) that could be like this.
