By Kent · Lock Depot Staff Writer

The second digit is the function

In the Simplex 5000 Series the last digit of the part number tells you the latch. The digit before it tells you what the lock does. The 5021, 5031, 5041 and 5051 all carry the same 70mm backset and the same half-inch latch throw. They are not interchangeable, because the tens digit changes what happens when you walk up to the door.

If you have read our piece on backset and latch throw on the 5021, 5022 and 5025, this is the other half of the part number.

The four listings side by side

Part	Function as listed	Passage mode	Backset	Latch throw
5021MWL-026-41	Combination Entry with Key Override	No	2-3/4 in.	1/2 in.
5031MWL-026-41	Combination Entry with Key Override (DOD)	No	2-3/4 in.	1/2 in.
5041MWL-026-41	Combination Entry with Key Override and Passage Mode	Yes, interior thumbturn	2-3/4 in.	1/2 in.
5051MWL-026-41	Combination Entry with Key Override and Passage Mode (DOD)	Yes, interior thumbturn	2-3/4 in.	1/2 in.

Two things move across that table: passage mode and a tag the catalog writes as DOD. Take them one at a time.

Passage mode: free entry without the code

The 5041 and 5051 add what the listing calls passage mode with an interior thumbturn. When the thumbturn is engaged, the door opens without the code. Turn it back and the keypad is in charge again.

This is the feature a front office wants. A reception door, a clinic suite, a classroom that stays open all morning. Someone on the inside turns the thumbturn at 7:30, people walk in and out all day, and someone turns it back at 4:30. You get the keypad for after-hours and an open door for business hours without hanging a second lock or propping the door.

The 5021 and 5031 do not have it. If the door is a back room that stays locked to the keypad all day, those two are the lock, and you are not paying for a thumbturn nobody will use. The risk on a passage mode lock is human, not mechanical. Someone leaves it engaged overnight and the door is open until morning. If the door guards something that matters, the plain 5021 is the safer part, because there is nothing to leave engaged.

DOD: what the catalog does and does not tell us

The 5031 and 5051 carry the tag DOD in parentheses after the function. The listing does not spell out what it stands for, and I am not going to guess at an abbreviation on a lock that protects somebody's door. What the listing does give you is this: the 5031 is the 5021 with the DOD tag, and the 5051 is the 5041 with the DOD tag. Nothing else in the specifications changes. Same Grade 1, same fire rating, same prep, same latch.

So the way to buy it is to find out what the DOD designation means on the door you are replacing. If the old lock has the tag on it, match it. If it does not, you most likely want the version without it. If you are not sure, send us the model number off the old lock and we will match it. Do not order the DOD version because it sounds like the more secure choice. Without the definition, you do not know what it changes.

What all four share

• All-mechanical. No batteries and no wiring.
• Combination changed at the keypad without removing the lock from the door.
• Solid metal pushbuttons, listed as vandal resistant, and weather resistant for indoor and outdoor use.
• ANSI/BHMA Grade 1 and 3-hour UL/ULC fire rated.
• Doors from 1-3/8 in. to 2-1/4 in. thick, on a 2-1/8 in. cross bore and 1 in. edge bore.
• Non-handed, shipped left-hand, field reversible.
• Three-year warranty.

All four are prepped for a Medeco LFIC key override, and in every case the core is sold separately. The key override and the code are two separate ways in. Passage mode is a third, and it comes from the inside.

Choosing between them

Ask three questions at the door.

1. Does this door stay open during the day? If yes, you want passage mode, which means the 5041 or 5051. If it is always locked to the keypad, the 5021 or 5031 is the lock.
2. What does the old lock say? Match the DOD tag if it has one. Do not add it and do not drop it.
3. Who has the key? Every one of the four needs a Medeco LFIC pinned to your system before the override works.

Those three answers pick one of the four. If the door is a different latch, a 60mm backset or a three-quarter inch throw, change the last digit, not the tens digit. The 5022 and 5025 sit in the same family with their own function twins in the 503x, 504x and 505x ranges. The catalog lists those with 1/2 in. throw and 2-3/8 in. backset, or 3/4 in. throw and 2-3/4 in. backset, in the same pattern.

Where this fits among the other Simplex numbers

The 5000 Series is a big family and the numbering is regular, which is the good news. The 5010 numbers are exit trim, covered in the 5010MWL and 5010XKWL article. The 5011, 5015, 5016 and 5017 are exit trim, sorted by latch, in this write-up. The 502x through 505x numbers are combination entry for a cylindrical prep, and the function is the tens digit.

A mechanical pushbutton is a fine answer where nobody wants a battery schedule. If you are weighing it against a wired option for a door that needs an audit trail, that is a different conversation. For a door that needs a code and a key, and nothing else, this is the lock.

Common questions

Which Simplex 5000 numbers have passage mode?

The 5041 and 5051. The listing describes an interior thumbturn that allows free entry without the code when engaged.

What does DOD mean on the 5031 and 5051?

The listing shows the tag in parentheses but does not define it. Call us with the model number off the old lock and we will match it.

Do the four share the same latch?

Yes, as listed: a 2-3/4 in. backset and a 1/2 in. latch throw on all four.

Is the Medeco core included?

No. All four are prepped for a Medeco LFIC key override and the core is sold separately.

Do any of these need batteries?

No. The Simplex 5000 Series is all-mechanical with no batteries and no wiring.

What is the warranty?

The listings state a three-year warranty.

More from this maker is on our Kaba Ilco and Simplex page. Call us if you need help matching the part number to the door you have in front of you.