Master Lock 6421 Pro Series We...
IN STOCK (leaves warehouse same day if ordered before 3pm ET)
$38.31
Master Lock Master Lock 6421 Pro Series Weather Tough IC Padlock 6421

Master Lock 6421 Pro Series Weather Tough IC Padlock

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Model: 6421LJWO

In Stock (leaves warehouse same day if ordered before 3pm ET)

$38.31
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OVERVIEW

  • Choice of 16 Small Format Interchangeable Cores to match this padlock to your door locks. See Related Information for options.
  • Ideal for harsh outdoor conditions - exclusive Weather Tough® cover protects lock from water, ice, dirt and grime
  • ProSeries® Padlocks are designed for Commercial/Industrial applications
  • 2-1/8in (54mm) heavy steel body withstands physical attack
  • 1-1/8in (29mm) tall, 5/16in (8mm) diameter hardened boron alloy shackle for superior cut resistance
  • Dual ball locking mechanism resists pulling and prying
  • Lock available with or without core. Accepts standard SFIC OEM cores.
  • Rekeyable 6- and 7-pin core options.

Manufacturer Resources

Product Specs

Subcategory:
Padlocks
Series:
6421 Series
Keyed:
Yes
Product Group:
Other \/ Miscellaneous Hardware
Product Subgroup:
Padlocks
Product Type:
Padlocks
Commercial/Residential:
Residential
Shackle Diameter:
5/16" (8mm)
Shackle Width:
7/8" (22mm)
Padlock Body Width:
2-1/8" (54mm)
Product Category:
Door Trim and Accessories
Department:
Door Hardware

Master Lock 6421LJWO – Frequently Asked Questions

1) Will the Master Lock 6421 padlock take the same SFIC core as my building's door locks?
Yes, if your doors run small format interchangeable cores. The 6421 Pro Series padlock accepts standard SFIC OEM cores, so it can be keyed into the same system as the cylinders already in your doors. There are 16 small format interchangeable core choices to match it to your door locks, and it can be ordered with or without a core, which is what you want if your locksmith is pinning cores in house.
2) What shackle lengths does the Master Lock 6421 padlock come in?
Four shackle lengths: 1-1/8, 1-3/8, 1-1/2 and 2-3/8 inches. Pick by how much clearance the hasp or chain link needs. The short 1-1/8 inch shackle leaves the least space for a bolt cutter jaw and is the choice for a tight hasp on a gate or utility cabinet; the 2-3/8 inch is what you need to get through a heavier chain or a thick hasp staple. All four carry the same 5/16 inch (8mm) shackle diameter and 7/8 inch (22mm) shackle width, so the shackle has to clear a 7/8 inch opening regardless of the length you order.
3) Will a Master Lock 6421 padlock fit my hasp?
Measure the hasp staple opening and the gap the shackle has to span. The 6421 shackle is 5/16 inch (8mm) in diameter, so the staple hole has to be at least that. Shackle width is 7/8 inch (22mm), which is the inside span between the shackle legs, so the hasp material has to sit inside that. Body width is 2-1/8 inch (54mm), so allow that much room under the hasp for the lock body to hang without fouling the frame or gate post.
4) Should I order the 6421 padlock with a core or without one?
Order it without a core if you or your locksmith already stock SFIC cores and pin your own, since the lock accepts standard SFIC OEM cores and you just drop your keyed core in with a control key. Order it with a core when you want it ready to key into one of the 16 core options offered to match your door locks. Core options are rekeyable in 6-pin and 7-pin, so match the pin count to whatever your existing system runs, a 7-pin core will not work in a facility keyed on 6-pin.
5) Can I standardize a whole property on the 6421 padlock and keep everything on one key?
Yes, and that is the reason to buy this one over a plain keyed padlock. Because the 6421 takes standard SFIC OEM cores, every padlock on the site can run the same core format as the door cylinders, so a master key or a maintenance key opens gates, cabinets and doors alike. Order the padlocks less core and have the same cores pinned for all of them. Keep the shackle length consistent per application, not per building, since the hasps vary.
6) Is the Master Lock 6421 padlock OK to leave outside year round on a gate or utility enclosure?
That is what it is built for. The 6421 carries a Weather Tough cover that keeps water, ice, dirt and grime out of the lock, and the shackle is hardened boron alloy for cut resistance. The ProSeries line is built for commercial and industrial use, so exterior gates, yard enclosures, roof hatches and equipment cages are the normal application.
7) How does the Master Lock 6421 hold up to someone prying or yanking on it?
Two things do the work. The body is 2-1/8 inch (54mm) heavy steel, which is what resists a physical attack on the lock itself, and a dual ball locking mechanism holds the shackle against pulling and prying rather than a single pawl. Cutting the shackle means getting through hardened boron alloy at 5/16 inch (8mm) diameter.
8) What is the difference between an interchangeable core padlock like the 6421 and a standard keyed padlock?
A standard keyed padlock has a fixed cylinder, so rekeying it means disassembling the lock or replacing it outright. The 6421 takes a small format interchangeable core, which pulls out with a control key in seconds and swaps for a differently keyed core. If a key walks off a job site or a tenant turns over, you change the core, not the padlock. Buy the fixed-cylinder type if you only need a handful of locks and no key system behind them; buy the IC version when the padlocks have to live on the same keying system as your doors.
How fast can I get the Master Lock 6421LJWO delivered?
Most orders ship the same day from our distribution partners, with quick delivery throughout the continental U.S. Need it urgently? Contact Us for expedited shipping options.
Can I return it if it doesn’t work for me?
Yes—ZenSupply offers a hassle-free return policy. If the product isn’t the right fit, reach out to our support team for a return authorization or setup a return by following our return instructions.
Does the Master Lock 6421LJWO come with a warranty?
Absolutely. The Master Lock 6421LJWO is backed by a manufacturer’s warranty. For full warranty terms, check the product documentation or Contact Us.
How do I get technical support or installation help for the Master Lock 6421LJWO?
You can call, text, or email our expert support team for fast answers. We’re here to help with product selection, installation tips, and troubleshooting. Contact Us
Why buy the Master Lock 6421LJWO from ZenSupply?
ZenSupply makes it easy to get the commercial door hardware you need—fast shipping, expert support, and rewards on every order. Our team is always ready to help you choose the right product for your project.
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