Home Safes · Master Lock
Master Lock 5900D
1.9/5 Best Safe Score (how we score)
My pick for practice, the beach or a school trip: a backpack-size box with a set-your-own 4-digit combination, no batteries and no key, a wrap-around cable and an earbud port. It holds a phone, keys and cards.
Details
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Who it's for
- Best portable lock box for a teenager in Best Safe for Teenager – 5 Picks Sorted by What a Teen Stores: Teens who need a phone and wallet locked to a bench or bleacher, and families who want a box only the teen can open; it is basic security, so it stops grabs, not tools.
- Best portable safe for the gym and library in Best Safe for a College Dorm Room – 5 Picks Sorted by What You Store: Students who need a phone and wallet locked to a bench or table outside the room; Master Lock rates it basic security, so it stops grabs, not tools.
What we like
- Set-your-own 4-digit combination, no batteries
- Cable wraps around a fixed object and doubles as a handle
- Earbud and charging-cable port; water-resistant build
- Cable doubles as a carry handle and wraps around a fixed object
What to know first
- Basic security only; a lock-picking channel showed the dials can be read
- No key, so a forgotten combination means a lockout
- A few Walmart owners locked themselves out after setting a combination
Product details
| Brand | Master Lock |
|---|---|
| Manufacturer | Master Lock |
| Model | 5900D |
| Part number | 5900D |
| Dimensions (L x W x H) | 5.5 inches x 9.53 inches x 2.25 inches |
| Item weight | 1.57 pounds |
| Color | Gunmetal Grey |
| Size | 9.8 x 5.5 x 2.6 inches |
| Warranty | One year limited warranty |
| Lock | Set-your-own 4-digit combination |
| Exterior | 2-1/4 x 9-17/32 x 4-59/64 in (H x W x D) |
| Interior | 1-1/4 x 8-1/8 x 3-1/2 in (H x W x D) (listing) |
| Weight | 0.71 kg (listing) |
| Anchoring | Wrap-around cable |
| Water | Water resistant (maker) |
| Fire rating | None claimed |
Top rows from the Amazon listing; the rest from the maker pages we checked.
About this item
- Small safe is ideal for use as a travel safe or personal safe for protection and security from theft
- Secure small safe to a fixed object with cable; Portable safe is best used to protect smart phones, passports, cash, and credit cards
- Set your own four-digit combination portable safe; Ear bud/charging cable access port to conveniently listen to music or charge devices while locked
- Constructed with a shock absorbing foam, small lock box is designed to be water-resistant
- Exterior dimensions: 2-1/4 inch H x 9-17/32 inch W x 4-59/64 D; Interior dimensions: 1-1/4 inch H x 8-1/8 inch W x 3-1/2 inch D
From the product's Amazon listing, as of Nov 7, 2026, 7:59 PM UTC. The seller writes this text, not us, and Amazon may change it.
What owners say
Summarized from 1 owner discussion and review page we read.
Praise
- Straps to a bed and fits in a backpack for travel
- Handy low-security box for medication and small items
Complaints
- One owner could not reopen it after setting the combination
- Rubber on the dial came off for one owner, and one got no instructions
Guides that include it
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