Every powerboat racing enthusiast's calendar with the 2016 P1 Superstock powerboats. Buy your copy NOW. The P1 SuperStock Championship is based on racing identical production boats - the stunning P1 Panther, competing in five Grand Prix of the Sea events each season. These events attract more than 150,000 spectators annually in Scotland, England and Wales. Calvendo calendars are premium products - a bit more pricey than others but with added benefits: Our calendars always look beautiful on your wall because we produce them locally with premium paper and sophisticated spiral binding, ensuring easy turning of pages and flat hanging against the wall. A protective transparent plastic cover sheet provides added stability. Treat yourself to a Calvendo calendar and you get something that looks better all year round.