BH101 T25 Star CSK T17 304EX 12-11×50 250




Fast Find: 101
Drive: T25 Star
Length: 50mm
Head: Countersunk + Ribs
Gauge: 12
Material: 304 Extreme Stainless Steel
Point: Type 17
Application: Decking Screw
Units Per Pack: 250

Blackhawk Fasteners X1 Decking Screws


Blackhawk 12 gauge, type 17, countersunk, 304 Extreme stainless steel, T25 star drive decking screw.

Decking screws come in a range of sizes and materials. Choosing the wrong screw can add unnecessary time and cost to your decking project. The Blackhawk X1 decking screws have a range of features that will improve your decking experience.

304 Extreme Stainless Steel

The screw material is one of the most import factors when making your purchasing decision. Getting this wrong can have a huge impact on the strength and durability of your deck. Blackhawk Power 8 decking screws are available in 304 Extreme stainless steel. 304 Extreme stainless steel has an improved formula when compared to standard 304 stainless steel. This results in a higher level of corrosion (rust) resistance. 304 Extreme Stainless steel:

  • Protects the screw from corrosion in most external applications.
  • Has an attractive silver finish
  • Has greater corrosion protection than standard 304 stainless steel

304 Extreme stainless steel is not recommended for applications within 1km of breaking surf or in close proximity to swimming pools.

There are a number of environmental factors that can contribute to premature corrosion of fasteners. These factors can be, but are not limited to the following:

  • Salt water and salty air carried from a salt water body
  • Preservative treated wood
  • Soils
  • Poor quality decking oil or decking paint

It is recommended that you discuss this with your builder or local council prior to commencing work.


The Blackhawk X1 decking screws are available in 50mm and 65mm lengths.

  • Gauge = the diameter of the threads (12 gauge = 5.5mm).
  • Length = the measurement from the top of the head to the tip of the point.

To determine the length of required screw, you will need to know the type of timber being used for both the decking and joists. When fixing into softwood joists, the screw should be 2.5 times the thickness of the decking board. When fixing into hardwood joists, the screw should be 2 times the thickness of the decking boards. Blackhawk X1 decking screws are not recommended for metal joists.

Blackhawk Fasteners have made the task of choosing the right screw easier for you. Simply visit the CHOOSING THE RIGHT SCREW page to work out what length, gauge and even corrosion resistance level you require.

Type 17 Point

Type 17 refers to the long cut section at the point of the screw. The type 17 point:

  • Helps to remove debris when being driven through the decking timber
  • Reduces the need to pre-drill your decking boards

Different species of decking timber have different hardness levels. This will determine the need for pre-drilling. It is recommended that you always pre-drill the ends of the decking boards as they are prone to splitting.

T25 Star Drive

The T25 star-drive has a 6 point, star-shaped pattern. The star-drive shape:

  • Increases the surface area that the tool connects with
  • Allows more torque to be applied when driving the screw
  • Reduces the chances of “cam-out” and damage to the screw or tool

“Cam-out” is a term used when the tool that is driving the screw slips out.

BLACKHAWK provides 2 free 50mm T20 star drive bit that are suitable for use in impact drivers.

Countersunk Head with Ribs

A countersunk head helps finish the screw flush with the surface of the deck. The Blackhawk Power 10 decking screws have integrated ribs on the underside of the head. This helps to remove excess timber, resulting in smoother, cleaner finish.

How many screws?

The Blackhawk X1 decking screws come in tubs of 250. The amount of screws that you will need depends on the size of your deck and the amount of joins you will have. Each join typically requires 4 screws. Most timber decking boards will come in random lengths. This makes it very difficult to pre-determine the exact amount of joins you will have, and therefore the amount of screws you will need.

Blackhawk has created a DECKING SCREW CALCULATOR to help you figure out how many screws you need. This will assist in reducing wastage and unnecessary added costs.