10 pcs  1/4-28x2D  Please google these and  check them out before buying. These have a different type of installer. I think.
 
BrandHELICOIL/STANLEY
FinishPlain
Free Coil Diameter (Max.)0.326in
Free Coil Diameter (Min.)0.306in
Insert Length0.500in
Material304 Stainless Steel
No. of Sides per Grip Coil5
Nominal Diameter0.250in
Number of Coils11 3/8
Number of Coils From End Insert5 11/16
Number of Grip Coils1
PackagingBulk
RoHSCompliant
Thread Size1/4-28
Thread TypeUnified Fine Thread (UNF)
TypeScrew-lock Inserts (internal-lock)
UnitsInch