Special Notes:May not work for spark plugs with a 13/16 hex size or bigger.The Tusk Spark Plug Holder is a must have for all trail packs or tool boxes. The spark plug holder accommodates all types and sizes of 2-stroke and 4-stroke motorcycle, ATV, and UTV style spark plugs. Designed with a tapered top and 3/8 inch wall, it cradles the spark plug and protects it against any hits or drops. The screw cap construction makes it easy to open and close. Think Tusk for all of your trail pack or tool box necessities.