DUNDOO 15Pcs Screw Extractor Set, Cobalt HSS Left Hand Drill Bits and Hex Head Extractors Review
Three kinds of bits for broken screws and frozen bolts, in one 15 piece kit
| Piece count | 15 |
|---|---|
| Multi-spline extractors | 5 |
| Spiral extractors | 5 |
| Left hand drill bits | 5 |
| Material | Cr-Mo steel and cobalt fortified HSS |
| Size marking | Engraved on the socket |
| Best for | Garage and workshop owners who occasionally face stripped screws or snapped bolts |
Product Overview
The DUNDOO set is a 15 piece kit aimed at one job: getting out a fastener that has stripped or snapped. It splits into 5 multi-spline extractors, 5 spiral extractors and 5 left hand cobalt drill bits, so the three common approaches are covered in one case.
The left hand drill bits matter more than they look. Spinning a bit counterclockwise while drilling a pilot hole sometimes grips the broken fastener and backs it out before an extractor is even needed. The extractors then handle the stubborn cases.
The listing says the kit is made from Cr-Mo steel and cobalt fortified HSS, and that it suits wood and metal work in construction, automotive and home projects. It lists both power tool and hand tool use.
What the listing leaves out is the size chart. It says sizes are engraved on the sockets, but does not state the range, which is the first thing to check against the fasteners you actually fight with.
Score Breakdown
This verdict is based on the manufacturer's stated specifications, the current Amazon listing and its product images, the confirmed materials and design, real buyer ratings, and our research into the product category. Scores are consistent editorial judgments, not laboratory measurements, and we did not receive a paid sample.
Key Features
Five pieces for gripping drilled out fasteners.
Five pieces with a high-density spiral design.
Five cobalt drill bits that cut while turning counterclockwise.
A hard material suited to cutting steel.
Sizes are marked on each socket.
Listed for construction, automotive and home projects.
Design and Build Quality
The kit uses a three-way split of 5 pieces each, which gives some choice in diameter within each type. Having both a multi-spline and a spiral style is helpful because they bite differently: one grips by wedging into a drilled hole, the other by a tapered spiral thread.
The material claim is Cr-Mo steel with cobalt fortified HSS. Cobalt HSS is a standard choice for drill bits that must cut hard or heat-treated material without dulling quickly. The listing does not give a hardness rating, so treat durability as the maker's claim.
The listing states that sizes are engraved clearly on the sockets. That is a practical detail when you are juggling several similar bits with greasy hands.
The part number in the listing is a simple internal label, and the listing does not name a storage case or describe its quality.
Performance in Everyday Use
The listing describes a high-density spiral design that is meant to remove damaged, rusted or frozen screws, bolts, nuts and studs faster. In practice, extractors work best when the hole is drilled straight and centered, and the left hand bits help with that first step.
Since the kit works with both power tools and hand tools, you can drill the pilot hole with a drill and turn the extractor by hand with a tap wrench for more control. Extractors are hard but brittle, so steady turning rather than hammering is the safer habit.
Stubborn rust or seized threads may still need penetrating oil and patience. No extractor kit can promise success on every fastener, and the listing does not either.
Fit across sizes is the open question. Without a stated range, buyers should compare the bits against the screws and bolts they expect to meet.
How It Performs: The Evidence
| Decision factor | What we found | Evidence and measurement | Score | Why it matters |
|---|---|---|---|---|
| Piece count | 15 pieces | Count in the listing | 8.8 | Covers drilling and extracting |
| Material | Cobalt fortified HSS | Material in the listing | 8.4 | Suited to hard fasteners |
| Extractor types | Multi-spline and spiral | Types in the listing | 8.6 | More than one grip style |
| Drill bits | Left hand cobalt | Bits in the listing | 8.4 | Can back out a fastener while drilling |
| Marking | Engraved sizes | Marking in the listing | 8.0 | Easy to pick the right bit |
| Size chart | Not given | Absent from the listing | 6.4 | Fit must be checked by you |
| Tool types | Power and hand tools | Use in the listing | 8.2 | Flexible technique |
Who Should Buy It
- Garage work
- Automotive repair
- Home DIY
- Workshop kits
- Rusted hardware
- Stripped screw rescue
- Professional mechanics who need a documented size range or a branded heavy duty line
- No size range stated in the listing
- No hardness rating is given
- Case quality is not described
- Material and durability claims are the maker's own
- No guarantee on rusted or frozen fasteners
Full Specifications
How It Compares
| Feature | DUNDOO | Typical option | Higher-tier option |
|---|---|---|---|
| Piece count | Large | Small | Medium |
| Extractor styles | Two | One | Two |
| Left hand bits | Included | Sometimes | Included |
| Material | Cobalt HSS | Plain steel | Cobalt HSS |
| Size marking | Engraved | Varies | Engraved |
| Size chart | Not given | Not given | Given |
Alternatives Worth a Look
The DUNDOO kit is a sensible all-in-one answer to stripped and broken fasteners, covering left hand drilling, multi-spline and spiral extraction. The missing size chart and unspecified case are the main reasons to check the dimensions of your own fasteners first.
Frequently Asked Questions
What is in the kit?
5 multi-spline extractors, 5 spiral extractors and 5 left hand cobalt drill bits.
What material is used?
The listing cites Cr-Mo steel and cobalt fortified HSS.
Can I use it with a drill?
Yes, the listing says it suits both power tools and hand tools.
Does it work on wood?
The listing says it suits wood and metal.
Are the sizes marked?
Yes, sizes are engraved on the socket.
Does the listing give a size range?
No, so compare against the fasteners you need to remove.
Will it remove any rusted bolt?
No kit can promise that. Rusted or frozen fasteners may still need patience.
This review is based on the product listing and manufacturer data, along with our own research into extractor and drill bit kits. It is not based on independent testing. Scores are editorial judgments built from the details the listing provides, such as piece count, materials and bit types, and should be read as a comparison with typical kits rather than as measured results.