Get the ‘W’ for outdoor extension cords.

Yes, the W means weather-resistant, and yes, you need it for outdoor use. SJTW, SOW, STW — the W is what keeps the jacket from cracking in sun and shrugging off water splashes.

A cord without W is indoor-only. Use it outside and UV rays will turn it brittle in a season, and moisture can get into the insulation and cause trouble you don’t want. Not worth it.

The W isn’t a suggestion. It’s the difference between a cord that lives on the deck and one that ends up in the trash.