While looking along the shores of the Isle of Mull (ie Scotland), I found a partial bottle that included the bottom and part of the sides walls. The raised marking, PSP, is found on the outside bottom. The bottle appears to be old by way of noticing the rather uneven thicknesses of the side walls and inside bottom. In fact, the inside bottom material thickness is worth noting. It measures about 2" across has a noticeable sloping appearance. The outside bottom is slightly concaved. The bottom appears black in color but only holding up to the sun can you see the true color which is a very dark green.
Looking forward to hearing your thoughts.
Looking forward to hearing your thoughts.