# Shark BU3521 Clean & Empty Cordless Stick Vacuum with Auto-Empty Dock

The 1.3-liter auto-empty base makes this cordless stick vacuum a practical choice for everyday carpet and hard-floor cleanup.

- [Original product page](https://www.ofertitastop.com/us/product/shark-bu3521-clean-empty-cordless-stick)
- [View offer](https://www.ofertitastop.com/us/visit/shark-bu3521-clean-empty-cordless-stick)
- Market: US
- Language: en-US
- Currency: USD
- Product updated: 2026-10-24T01:46:52.347Z
- Brand: Shark
- Model: BU3521
- EAN / GTIN: 10622356647462
- SKU: ofertitastop-us-161069
- Category: Home & Garden > Household Appliances > Vacuums
- Source store: amazon US
- Active deal: Yes
- Price: 279.00 USD
- Previous price: 399.99 USD
- Discount: 30%
- Rating: 4 / 5
- Reviews: 2483

Prices and deal status are the latest recorded data, not a guarantee of availability. Confirm the price and availability with the store.

## Description

With a 1.3-liter auto-empty base, the Shark Clean & Empty BU3521 gives cordless floor cleaning a convenient home between sessions. Dock the vacuum after use and it automatically empties and charges, so it’s ready for the next round of cleaning.

Its stick format handles everyday passes across carpets and hard floors, while the removable hand vacuum makes it easier to clean furniture, stairs, and other above-floor areas. The included crevice tool and Pet Multi-Tool add options for edges and pet hair.

If you want a cordless vacuum that you empty by hand, a standard stick model keeps the routine simple. If you’d rather have a dock take care of emptying after each clean, the BU3521 brings that step into its charging setup.

## Tips for day-to-day use

Use the stick vacuum for floors, then detach the hand vac when you move to furniture, stairs, or smaller spots. The crevice tool is suited to narrow spaces, while the Pet Multi-Tool is included for pet-hair cleanup. For a mixed-floor home, the auto-adjusting brushroll changes its speed to suit carpet or hard floors, helping the vacuum adapt as you move from one surface to another.

After cleaning, return the vacuum to its dock for automatic charging and emptying. The 40-minute runtime is measured in ECO mode at the hand vacuum, which is a useful reference when planning a cleaning session. The self-cleaning brushroll is designed to help prevent hair wrap, an especially practical detail for homes where hair pickup is part of the regular routine.

## What you’ll notice day to day

The dock handles the transition between cleaning and storage: the vacuum empties into the base when docked, rather than requiring manual emptying after every session. Its sealed HEPA filtration system captures and traps over 99.97% of dust and allergens down to 0.3 microns, based on the stated test standard, allergens here refers to non-living matter.

Buyers often praise the self-emptying feature and report good performance on wood floors. Feedback is more mixed on battery life, suction, and hair pickup, and some buyers mention handle durability concerns. These impressions can help set expectations, while the listed features explain how the vacuum is designed to handle routine floor and above-floor cleaning.

## At a glance

- Type: Cordless stick vacuum with auto-empty system
- Capacity: 1.3-liter auto-empty base
- Runtime: Up to 40 minutes in ECO mode, measured at the hand vacuum
- Filter: HEPA filtration with anti-allergen complete seal
- Included: Auto-empty base, cordless vacuum, crevice tool, and Pet Multi-Tool
- Power: Rechargeable lithium-ion battery
- Color: White

## Before you decide

**How long can it run on a charge?** It offers up to 40 minutes of runtime in ECO mode, measured at the hand vacuum. Actual cleaning plans can account for the selected mode and whether you’re using the stick vacuum or detached hand vac.

**Does it work on both carpet and hard floors?** Yes. The auto-adjusting multi-surface brushroll optimizes its speed for deep carpet cleaning and hard floors, making it suitable for homes with both surface types.

**What happens when you dock the vacuum?** It automatically charges and empties debris into the 1.3-liter base, where dust and debris are sealed away after cleaning.

## Buying verdict

The BU3521 is a practical fit for shoppers who want one cordless system for carpets, hard floors, stairs, and furniture, with a dock that automatically charges and empties the vacuum. Its removable hand vac, surface-adjusting brushroll, and included pet-hair tool make it especially useful for varied everyday cleanup around the home.

## Images

![Shark BU3521 Clean & Empty Cordless Stick Vacuum with Auto-Empty Dock — 1](https://www.ofertitastop.com/i/VV2cHZtiOzefX8N0jd1484HukfSub0mQRgOKhwRiBHBTLxxa5Fa6HACsNpdtZnXkpdTNRDve1GeKOgd0dcCXQbQNJc_E5xIRsJHhuXOEQtcC5jAQT6g_ydjEbA.jpg)

![Shark BU3521 Clean & Empty Cordless Stick Vacuum with Auto-Empty Dock — 2](https://www.ofertitastop.com/i/OjPJn6W_mVkMTwf5wK__TQvFxXKHXrjjW6ppOkiLvzjg7Nhw3aiqzreory-3aIeUz5hyTfcPQ_iMQNRFzjJXC2YBnaxYaoKDG_v1-qDirKKolNeSwfQH8oVnlg.jpg)

![Shark BU3521 Clean & Empty Cordless Stick Vacuum with Auto-Empty Dock — 3](https://www.ofertitastop.com/i/mqeYCYSzCuo1uE-ozfPPzhz7jS4IaE8Cemt7PSG_HtobHLLl2ZdM5x273JbklL7RypUBfkg0oTqrlVmE6L0rkwA7LD3Q5kd04lX5gM4eQBkwpfhsXYOSaFAuig.jpg)

![Shark BU3521 Clean & Empty Cordless Stick Vacuum with Auto-Empty Dock — 4](https://www.ofertitastop.com/i/5kWNgk4cpj50LSvzxCzdKoHT9Dl9Zl3PZe2I8k1K8VVXuz_sBM67EekNHRWOOmgt1EJzduTXa1oW5sO5uBKWbwzhTH8w3puveeyUB5fKx4pggEI8.jpg)

![Shark BU3521 Clean & Empty Cordless Stick Vacuum with Auto-Empty Dock — 5](https://www.ofertitastop.com/i/FNRa8E1AyEWrP5NTzWM3t7zsen2EPPrVAgu5XPyVGYYbP9o2kAPy_q2VGmvyBL4l8xrdUdhZJF5Uf7q14tIrtcOhf_UYNC57_hSb1YMNNp-Mkjm6iIKmWpAbag.jpg)