Introduction
This manual provides detailed instructions for the setup, operation, maintenance, and troubleshooting of your vretti Bluetooth Thermal Shipping Label Printer, Model 420B. Please read this guide thoroughly to ensure proper use and optimal performance of your device.
Product Overview
The vretti 420B is a compact and efficient thermal label printer designed for various labeling needs. It supports both wired (USB) and wireless (Bluetooth) connectivity, offering flexibility for different operating environments.
Key Features:
- Bluetooth Connectivity: Print wirelessly from Android, iPhone, iPad, and Windows devices. (Note: Mac OS devices are not supported via Bluetooth).
- High-Speed Printing: Capable of printing up to 75 labels per minute (152mm/s) at 203 dpi resolution for clear black and white text and images.
- Versatile Media Support: Compatible with various thermal direct label types including Continuous, Gap, Black Mark, Fan-Fold, and Punched Hole.
- Adjustable Label Sizes: Supports label widths from 25.4mm to 115mm (0.78 to 4.6 inches), accommodating shipping labels, address labels, barcode labels, and more.
- Multi-Platform Compatibility: Works with major transportation and e-commerce platforms such as UPS, eBay, Amazon, Shopify, FedEx, DHL, and Uber Eats. Compatible with Windows, Mac OS, and Linux systems via USB.
- Ink-Free Thermal Printing: Utilizes thermal printing technology, eliminating the need for ink cartridges or toner.
- Automatic Label Detection: Features auto label detection and error reprint technology for high-precision printing.
- Built-in Label Bin: Designed with an internal label bin, removing the need for an external label holder.
Setup
1. Unboxing and Components
Carefully unpack the printer and verify that all components are present:
- vretti 420B Thermal Label Printer
- Power Adapter and Power Cable
- USB Cable
- Quick Start Guide
- Safety Guide
- Sample Labels
- USB Adapter for Mac (if included)

Image: The vretti 420B printer shown with its power adapter, USB cable, and sample labels, illustrating the complete package contents.
2. Physical Connection
- Connect the power adapter to the printer's power port.
- Plug the power cable into a wall outlet.
- For USB connection, connect one end of the USB cable to the printer and the other end to your computer.
- Turn on the printer using the power switch located at the back.

Image: The vretti 420B printer connected to a laptop, demonstrating the USB connection setup.
3. Driver Installation (for USB Printing)
For Windows, Mac OS, or Linux systems, download the appropriate driver from the official vretti website. Follow the on-screen prompts to complete the installation.
- Visit the vretti label printers official website.
- Locate and download the driver for Model 420B compatible with your operating system.
- Run the installer and follow the instructions.
4. Mobile App Installation (for Bluetooth Printing)
For printing from Android, iPhone, or iPad devices via Bluetooth, install the dedicated mobile application:
- For Android: Search for "4barcode Edit" in the Google Play Store.
- For iPhone/iPad: Search for "4barlabel" in the Apple App Store.
- Install the app on your device.

Image: A smartphone screen showing the "4barcode" app available on Google Play and the App Store, with the vretti printer connected wirelessly.
Operating Instructions
1. Loading Labels
- Open the printer cover.
- Adjust the movable guides to match the width of your labels.
- Insert the thermal labels into the printer with the printable side facing up. Ensure the labels are fed smoothly and correctly.
- Close the printer cover. The printer will automatically detect and calibrate the label size.

Image: Hands loading fan-fold labels into the vretti 420B printer, highlighting the adjustable guides for different label widths.
2. Printing via USB (Windows/Mac/Linux)
- Ensure the printer is connected to your computer via USB and the driver is installed.
- Open the document or image you wish to print.
- Select the vretti 420B printer from your printer options.
- Adjust print settings (e.g., label size, orientation, copies) as needed.
- Initiate the print job.
3. Printing via Bluetooth (Android/iPhone/iPad)
- Ensure Bluetooth is enabled on your mobile device.
- Open the "4barcode Edit" (Android) or "4barlabel" (iOS) app.
- Within the app, connect to your vretti 420B printer via Bluetooth.
- Select the type of content you want to print (e.g., PDF, image, custom label).
- Customize your label using the app's editing features (text, icons, images, barcodes, QR codes).
- Adjust print settings (e.g., width/height, copies, print quality, print speed).
- Tap "Print" to send the job to the printer.

Image: The vretti 420B printer in action, producing a shipping label, while a smartphone shows the connected mobile application.
4. Customizing Labels
The mobile application provides extensive customization options:
- Text: Add and format text with various fonts, sizes, and styles.
- Icons/Images: Insert pre-loaded icons or upload your own images.
- Barcodes/QR Codes: Generate and print standard barcodes and QR codes.
- Templates: Utilize pre-designed templates for common label types (e.g., address labels, product labels, thank you stickers).

Image: A display of diverse labels printed by the vretti 420B, showcasing its versatility for different shapes and purposes.
Maintenance
Regular maintenance ensures the longevity and optimal performance of your printer.
- Cleaning the Print Head: Use an alcohol wipe to gently clean the print head if print quality degrades or lines appear. Ensure the printer is off and cooled down before cleaning.
- Cleaning the Platen Roller: Regularly clean the rubber roller to prevent dust and adhesive residue buildup, which can affect feeding.
- Storage: Store the printer in a clean, dry environment away from direct sunlight and extreme temperatures.
- Label Quality: Use high-quality thermal labels to prevent damage to the print head and ensure clear prints.
Troubleshooting
Here are solutions to common issues you might encounter:
| Problem | Possible Cause | Solution |
|---|---|---|
| Blank Labels | Labels loaded incorrectly (printable side down). | Ensure thermal labels are placed with the printed side facing up. |
| Poor Print Quality (faint/unscannable) | Low print density, dirty print head, or low-quality labels. | Increase print density in settings. Clean the print head with an alcohol wipe. Use recommended thermal labels. |
| Printer Not Responding | Loose cable connection, incorrect driver, or Bluetooth not paired. | Check all cable connections. Reinstall printer driver. Ensure Bluetooth is correctly paired in the app. |
| Labels Not Feeding Correctly | Incorrect label size setting, misaligned guides, or label jam. | Verify label size settings in the app/driver. Adjust label guides. Clear any jammed labels. |
Specifications
- Model: 420B
- Brand: vretti
- Printing Technology: Thermal
- Connectivity: Bluetooth, USB
- Print Resolution: 203 dpi (black and white)
- Max Print Speed (Monochrome): 72 labels/minute (152mm/s)
- Max Media Size: 4 x 6 inches
- Supported Label Width: 25.4mm - 115mm (0.78 - 4.6 inches)
- Product Dimensions: 21 x 17 x 15 cm; 2.09 kg
- Special Features: High Speed Printing, Adjustable Width, Versatile Media Support, Multi-Platform Compatibility, Automatic Label Detection.
Warranty and Support
For warranty information or technical assistance, please refer to the contact details provided in your Quick Start Guide or visit the official vretti website. Ensure you have your product model number (420B) and purchase details ready when contacting support.
Contact Information:
- Email: support@vretti.com
- Website: www.vretti.com





