sales@foscoconnect.com
(510) 319-9878
Silicon Valley, CA, USA
The Proto J4990-6MXL is a 3/8-inch drive, 6mm metric extra-long hex bit socket designed to provide extended reach for deeply recessed fasteners. Manufactured from heat-treated alloy steel, this bit socket ensures high strength and durability in industrial, mechanical, and heavy-duty maintenance applications.
It features a corrosion-resistant polished chrome finish on the socket base for easy cleaning and protection against harsh workplace environments. The extra-long bit profile allows technicians to maintain optimal torque and clearance when accessing confined or hard-to-reach hex fasteners.
Product Specifications
- Manufacturer Model: 4990-6MXL
- Drive Size: 3/8 inch
- Tip Size: 6 mm (Metric)
- Profile: Extra Long Hex
- Overall Length: 6-3/32 inches
- Material: Heat-treated alloy steel
- Finish: Polished chrome socket base
Frequently Asked Questions
What is the advantage of the extra-long hex bit design?
The extended length (6-3/32 inches overall) allows technicians to reach fasteners that are deeply recessed, obstructed, or located in tight clearances that standard-length bit sockets cannot properly engage.
Is the Proto J4990-6MXL suitable for use with impact tools?
No, this polished chrome and heat-treated alloy socket is designed strictly for use with manual hand tools, such as ratchets or torque wrenches. It is not rated for pneumatic or electric impact tools.

