I have an Optimus 300 and an Optimus 300P. Both lanterns have seen a lot of use, but they are still in good working order. I think the 300 is older than the 300P, but I am not sure. The two lanterns look very alike. I have taken these pictures to show the differences. The 300 is on the left, the 300P is on the right. Can you help me date these two lanterns? Sven Note the different arrangement of the pump, filler cap and fuel gauge cap. The 300 has embossed rims over and under the lower air inlet openings. The 300 has a nickel plated top cap (now burned black) with small openings. The 300P has a red cap with large openings. The markings on the tanks are very different. Different spirit cups. 300P has larger holes in the bottom plate. The regulator knob of the 300 is a simple disc with 3 slots and a notch. The 300P has a smarter designed knob with a washer with a small pointer. Both generators are placed in the center of the tank and are very alike. The tanks are different at the generator attachments. Note the different arrangement of the pump, filler cap and fuel gauge cap.