The Smoke Pellets No. SP was produced from 1947 until the end Post War period with the exception of the year 1967. As such, there is a wide variation in the size, shape and composition of these bottles.
From 1941 until 1947 Lionel produced a series of Chemistry Sets. One of the components of these sets were round BROWN colored bottles to contain the various chemicals. This bottle was adapted for use as a container for the smoke pellets during the early post war years. Of course, even for the few years that these bottles were available, Lionel made them with two different types of caps.
Other styles of bottles soon followed — some were square and some were round, some were short and some were tall, some had metal caps and some had plastic caps. However many varieties of these bottles were made has not, to this date, been defined. By comparing the mold number on the bottom of the bottles this is an area ripe for collectors who will eventually define the limits of these variations.
Dealer boxes for these bottles are not nearly as common as are the bottles. They contain twelve bottles that were separated by dividers and came in several varieties. No dealer boxes have yet to be found for the very early Post War round BROWN bottles.
There were fifty pellets in each bottle. While over the intervening years since these were manufactured some of the contents may have broken up and settled, they will, none the less, still work in the heat coiled smoke units. However, collectors place more value in contents that are complete with unbroken pellets and that have a complete intact bottle label.