This roller is called a Double Ended Dildo.

This shape of roller used to be quite rare.  There was a large cache of these rollers found in Japan in 2021, so they're not rare anymore in fact they are common.

These Double Ender's now serve as a cautionary tale to collectors that a float that's very rare can become common at any time if a large number of them are suddenly found.

This particular double ender has a two tone quality to it, where one end is a little bit darker shade of green and than the other end.

It measures 6 1/2 inches in length.