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White square box fan with carry handle and front grille

Lasko

Lasko 3720 20" Box Fan White

SKU CH-X72J-7W3AE MPN 3720

A 20 inch box fan with three quiet speeds, a weather-shield motor for window use and a stable wide body

  • Fan blade size20 in (50.8 cm)
  • Speed setting3 speeds
  • Product typeBox Fan
  • HighlightsIsolated Weather Shield Motor for Worry-Free Window Use High
  • Product colorWhite
  • Overall height22.5 in (57.2 cm)
  • Weather-Shield motor allows safe window placement
  • Wind Ring system delivers 30% more air velocity
  • Three whisper-quiet speeds suit any room
  • Wide base and 10.17 lbs weight prevent tipping
  • Save-Smart efficiency runs under 2¢ per hour

Product Identity

The Lasko 3720 is a 20" box fan built for residential cooling. Its Weather-Shield motor allows safe operation in open windows while the wider base provides stable floor placement. Three whisper-quiet speeds suit bedrooms, living rooms or home offices.

Deciding Specification

The isolated Weather-Shield motor is the feature that determines fit. It protects internal components from moisture during window use, a capability standard box fans lack. Buyers who need a fan strictly for dry indoor floors do not require this protection.

Build Integration

The fan measures 22.50" high, 21.25" long and 4.75" wide at 10.17 lbs. A built-in carry handle eases relocation between window and floor positions. Simple no-tools assembly gets it running in minutes. The Blue Plug safety fuse interrupts power if a fault occurs. U.L. and E.T.L. listings confirm compliance with recognised safety standards.

How it compares

Measured against everything we stock in Pedestal, Table & PC Fans, at today’s prices. Recalculated every night.

Price $34.99
Typical for this category: the median of 302 items is $31.99.

Specifications

Product
Brand nameLASKO
Model name3720
Product typeBox Fan
Product colorWhite
Performance
Speed setting3 speeds
Size & build
Fan blade size20 in (50.8 cm)
Overall height22.5 in (57.2 cm)
Overall width4.75 in (12.1 cm)
Overall length21.25 in (54 cm)
Product weight10.17 lb (4.61 kg)
Shipping weight3.74 kg
Package size597 × 546 × 127 mm

Questions about this item

How much air velocity does the Wind Ring system actually add in a room?

The Wind Ring system increases air velocity by 30 percent over a standard grille, pushing a stronger breeze across the space.

What safety listing does the Blue Plug fuse technology carry?

The fan is E.T.L. Listed, meaning the patented Blue Plug safety fuse meets recognised North American safety standards.

Will the 22.50-inch height and 4.75-inch depth fit on a typical windowsill?

At 22.50 inches tall and only 4.75 inches deep, the unit sits securely on most standard sills without overhang.

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