The word "pentomino" comes from the Greek word for 5 and "domino".  Each of the 12 pieces are made from 5 equal sized squares in different combinations resembling letters. The pieces can fit together to fit different size rectangles with many possible solutions:

• To create a 6 x 10 rectangle, there are 2339 solutions.   
• The 5 x 12 rectangle has 1010 solutions.
• The 4 x 15 rectangle has 368 solutions.
• The 3 x 20 rectangle has just 2 solutions.

2 sizes of puzzles are available, small or medium.