The 5pc steel spiral screw extractor is the perfect solution for removing screws and bolts, specially for removing rusted or rounded damaged ones. 

This extractor feature black-oxide threads for long-lasting performance. 
Contents:

5pc screw extractors

• No.1 1/8" - 1/4"  (3 - 6 mm)
• No.2 1/4" - 5/16" (6 - 8 mm)
• No.3. 5/16" - 7/16" (8 - 11 mm)
• No.4. 7/16" - 9/16" (11 -14 mm)
• 1pc  tap wrench for M1-10 tap.