The Master Lock 175D gives you 10,000 possible combinations on a resettable 4-digit lock that doesn’t need keys. For Montana contractors juggling multiple job sites and crew access, that’s the difference between managing a ring of keys and setting a code everyone knows. At 2 inches wide with a solid die-cast metal body and hardened steel shackle, it handles Montana winters better than locks that freeze up when moisture gets in the keyway.
Skip it if you’re securing high-value equipment or need insurance-grade security. Combination locks trade maximum security for convenience. But for storage units, tool boxes, and trailer compartments where multiple people need access, the 175D earns its keep.
Keyless Security That Actually Works
The 4-digit combination gives you 10,000 possible codes to choose from. More importantly, the included reset tool lets you change that combination whenever crew members leave or access needs change. No locksmith visits. No replacement cores. Just push the tool in, set your new code, and you’re back in business.
The combination mechanism beats keyed locks in one critical Montana scenario — winter. When it’s -20°F and your crew needs into the storage container, nobody’s fishing for keys with frozen fingers or dealing with locks that won’t turn because moisture froze in the cylinder. Those large dials work even with gloves on.
Resetting takes less than a minute: open with the current code (ships at 0-0-0-0), insert the reset tool into the hole on the lock body, turn 90 degrees, dial in your new combination, turn the tool back, and remove it. The new code activates immediately.
Built for Montana Weather
The solid die-cast metal body with brass finish and hardened steel shackle deliver weather-resistant construction rated for indoor and outdoor use. That brass finish isn’t just cosmetic — it resists corrosion better than painted steel when exposed to road salt and spring runoff.
| Specification | Value |
|---|---|
| Body Width | 2 in (51 mm) |
| Shackle Diameter | 5/16 in (8 mm) |
| Vertical Clearance | 1 in (25 mm) |
| Horizontal Clearance | 1 in (25 mm) |
| Weight | 0.53 lbs |
| Warranty | Limited Lifetime (mechanical defects) |
That 5/16-inch hardened steel shackle resists bolt cutters and hacksaws — not fortress-level security, but enough to deter opportunistic theft on job sites. The 1-inch clearance fits standard hasps with room to spare.
Where It Makes Sense
Master Lock positions this for residential gates, storage units, lockers, tool boxes, and RV compartments. In Montana construction, it shines for:
- Conex containers and job site storage where multiple trades need access
- Equipment trailers that move between sites
- Temporary fencing and site gates during rough-in
- Tool cribs and gang boxes shared by crews
The combination format solves the eternal job site problem — who has the key? Set one code for the GC, another for subs when they’re on site, then change it when the job wraps up.
The Trade-offs
No lock is perfect. Reviewers flag that combination locks can be vulnerable to manipulation techniques if someone has time and knowledge. The 175D trades maximum security for convenience. It won’t stop a determined thief with power tools, but it will prevent casual access and give your insurance company something to work with.
Master Lock makes variations if the standard 175D doesn’t fit: the 175DLH adds a longer 2-1/4 inch shackle, the 175DWD uses 4-letter word combinations instead of numbers, and the M175XDLF steps up to their Magnum series with a boron-carbide shackle.
Bottom Line
The 175D earns its place on any job where convenient access matters more than maximum security. At around half a pound with proven weather resistance and that lifetime warranty on mechanical parts, it’s built for the long haul. The resettable combination eliminates key management headaches while the brass-finished body and hardened shackle handle Montana’s weather swings.
For high-security applications, look elsewhere. For everything else — job boxes, storage units, equipment access — the 175D delivers exactly what contractors need: reliable, keyless security that works when it’s cold, wet, or both.
Frequently Asked Questions
How many combination options does the Master Lock 175D provide?
The 175D offers 10,000 total combinations using its 4-digit numeric system. That’s enough to prevent casual guessing while keeping the combination simple enough to remember and share with crew members.
Is the combination user-changeable?
Yes, the lock includes a reset tool for changing combinations. The process takes under a minute: open the lock, insert the tool into the reset hole, turn 90 degrees, set your new 4-digit code, turn the tool back, and remove it.
What comes with the Master Lock 175D?
The package includes the 175D padlock itself, a combination reset tool (also called a change key), and an instruction manual. The lock ships with a default combination of 0-0-0-0.
How does the 175D handle freezing temperatures?
The lock features weather-resistant construction rated for both indoor and outdoor use. The keyless design eliminates the common winter problem of moisture freezing inside key cylinders, and the large dials remain operable even when wearing gloves.
What size hasp or opening does the 175D fit?
The shackle measures 5/16 inch (8mm) in diameter with 1-inch vertical and horizontal clearance. This fits any hasp with holes at least 5/16 inch in diameter.
Ready to Get Started?
Our doors & millwork specialists can help you find the right Master Lock products for your project.
More from Master Lock
Explore All Master Lock Products
We carry Master Lock across all 11 Montana and Idaho stores.
