2 Pack N835578 Lawn Mower Safety Key Compatible with DeWalt Lawn Mower DCMWSP244U2 DCMWSP255Y2 DCMWP233U2

What It Is

This is a two-pack of replacement safety keys (interlock switches) for DeWalt cordless walk-behind lawn mowers. The key must be inserted and turned to start the mower; it also disables the battery power when removed, preventing accidental starts.

Fitment & Compatibility

Check your model number – this key fits only these specific DeWalt mowers: DCMWSP244U2, DCMWSP255Y2, and DCMWP233U2. It does not fit other DeWalt lawn tools or mower models.
OEM vs aftermarket – this is an aftermarket (non-DeWalt) part, but it matches the OEM N835578 part number in shape and function.
Physical check – measure the key’s blade width (approx. 0.5 in.) and the slot depth on your mower. If your original key is broken or lost, compare the slot shape (the key has a small notch on one side) to ensure it will seat fully.
What to avoid – do not buy if your mower uses a different safety system (e.g., a blade brake clutch or a push-button start without a key).

Key Things to Know

• Installation is trivial – just insert the key into the slot and twist to the “on” position. No tools or disassembly required.
• Quality note – some users report the plastic feels slightly lighter than the OEM key, but it works reliably for starting and safety shut-off.
• Common gotcha – if the key doesn’t turn smoothly, check for debris or bent contacts in the slot. Do not force it.
• Two-pack value – having a spare is smart since losing the only key leaves the mower unusable. The pack is cheaper than buying a single OEM replacement.

Should You Buy It

Buy this if you own one of the listed DeWalt mowers and need a cheap, functional spare or replacement safety key. It’s a no-brainer for $5.99 – the two-pack gives you a backup, and the 4.7-star rating confirms it works as intended. Avoid if you need an OEM part for warranty compliance or if your mower model isn’t on the compatibility list.