T-nuts are available with 3 or 4 prongs, each with its own advantages. Generally, 3-prong nuts are used for plywood, 4-prong nuts for hard or soft wood.
Propell nuts excel in applications where there is a danger of splitting, either due to material hardness or material thickness. They are also good for end-grain applications, such as leveller feet.
The T-nuts have 7/8" dia. flanges, a 3/8" barrel height, and a 9/32" prong height; the Propell nuts have 7/8" dia. flanges with a 5/8" barrel height; both require a 3/8" pilot hole.
Sold in packages of 10 or 100.