Try-Rex® Intermediate Pencils
The Try-Rex was America's first triangular pencil. Its beveled triangular shape was patented by pencil-maker Richard Best in the early 20th century and to this day no other pencil is quite the same shape.
As for the size, a mini-jumbo is an unusual size between a normal diameter pencil and a jumbo pencil. You'll find it to be exceptionally easy to grip and is recommended for long-haul writing. Box of 12.