E-Z LOK SK31020 3/8-24 standard coil kit with 2D inserts

Check compatibility
SK31020 is the standard 3/8-24 coil kit with a listed 0.750-inch installed length. Compare with EK31010 when the same repair thread calls for a shorter insert.
Questions before ordering
When should I choose the longer 3/8-24 coil?
The listing identifies a 0.750-inch installed length. Confirm the depth and compare the shorter EK31010 economy kit if the application calls for 1D.