12-Point Flange Counterbore Screw, Alloy Steel, Plain Finish, Fine Thread, 1/2-20 x 3-1/2"
(Pack of 10)

SKU:55953 Item#: 55953

Lawson Products

• Countr-Bor Screws generate higher clamp loads because they are torqued through an external drive (socket); standard hex socket head screws are torqued by an internal drive (hex key)
• Heat-treated alloy steel
• Class 3A UNC threads
• Tensile strength: 180,000 PSI (up to and including 1/2" dia.); 170,000 PSI (over 1/2" dia.)
• ANSI Specification B1.1
• All dimensional properties meet IFI-115 and SAE J58 specifications
• Lawson Countr-Bor Screws can replace any standard hex socket head screw
• 12-point screw fits into same counter-bore hole – use standard 12 point socket
NOTE: Use a wrench or socket size which corresponds to the diameter of the screw. For example, a 5/16" dia. screw is installed by using a 5/16", 12 point standard socket.

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Product Description

• Countr-Bor Screws generate higher clamp loads because they are torqued through an external drive (socket); standard hex socket head screws are torqued by an internal drive (hex key)
• Heat-treated alloy steel
• Class 3A UNC threads
• Tensile strength: 180,000 PSI (up to and including 1/2" dia.); 170,000 PSI (over 1/2" dia.)
• ANSI Specification B1.1
• All dimensional properties meet IFI-115 and SAE J58 specifications
• Lawson Countr-Bor Screws can replace any standard hex socket head screw
• 12-point screw fits into same counter-bore hole – use standard 12 point socket
NOTE: Use a wrench or socket size which corresponds to the diameter of the screw. For example, a 5/16" dia. screw is installed by using a 5/16", 12 point standard socket.

Technical Specifications

Item#: 55953
Type Counter-Bor
Diameter 1/2 "
Thread Pitch 20
Thread Fine
Length 3-1/2 "
Finish Plain
Material Alloy Steel
Head Style 12-Point Flange
Size 3-1/2 "
Specifications IFI-115
Tensile Strength 180,000 PSI
UNSPSC #: 31161620
TAA Compliant: Yes
Weight: 2.26 lb

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