The SMP Enlarger Extension Rods give you the chance to achieve greater gains through use of the SMP Enlarger. While the standard rods that come with the SMP Enlarger have a top length of 5", the extension rods have a top length of 7.5". That offers a full 2.5" of additional length over the original SMP Enlarger. Each package comes with two rods (the SMP Enlarger is sold separately).