YOOPAI Filament Dryer Box S4

This SUNLU S4 filament dryer absolutely works like a champ. It heats up quickly, maintains a stable temperature, and the automatic humidity control is a great feature that I didn’t realize I needed until I had it. I love that it can handle four spools at once—super convenient for anyone who prints often or rotates between materials. The upgraded fans circulate air evenly, and I’ve already noticed a big improvement in print quality with moisture-sensitive filaments like PETG and TPU. The whole unit feels well-built and easy to operate. If you want a reliable, efficient filament dryer that just works, this is a great pick.

The SUNLU S4 Filament Dryer Box is absolutely flawless. It arrived exactly as described and works perfectly right out of the box. The ability to dry four spools at once is a huge time saver, and the results are consistent—no more moisture issues or printing problems. The build quality feels solid, the controls are intuitive, and the temperature holds steady throughout the cycle. I’ve run multiple types of filament through it (PLA, PETG) and every spool came out dry and ready to print with noticeably improved performance. This product does exactly what it promises, and it does it reliably. For anyone serious about 3D printing, this is a must‑have accessory.

Solid drier. I print a lot of filament and a single spool dryer just wasn't going to cut it for my needs. This 4 spool dryer works well and does exactly what i need. I really like that it has outlets for using as a dry and print box. I print directly from this dryer on my bed slingers and the quality had really improved printing from a dry roll. Keeping your filament dry is keep to reducing stringing and having it stay within the box helps reduce tangles. The dryer has a solid amount of preset choices for temperatures for a variety of filaments, but you can fine tune it for any specialty filament. My only wish would be that it was split and could dry 2 types of filament at the same time. However I just throw them in as a little extra temperature doesn't appear to affect my PLA when drying with PETG.

I have used this dryer with one roll, 2, 3 and 4 rolls at a time. Performs as expected each time. I have dried pla, petg, and abs. Make sure your spool is also rated for the drying temperature of the filament.

I have been using the JAYO S1 for a while. It is the most basic of filament dryers. To say the S4 is an upgrade would not do it justice. the S4 is in a completely different category altogether. The S4 comes with a few pieces of tubing so that you can run the filament to your printer without exposing to the open air. Also included are some desiccant packets that can be placed inside the compartments under the spools to provide ongoing dehydration. Each of the 4 spool locations has an option for the filament to load out of the top or out of the end. Overall 8 different output holes. Each output is equipped with a connector that is designed to hold a bowden tube securely. For the outputs not in use SUNLU has provided small rubber plugs to keep the unit sealed. The build quality of the unit is excellent. Everything feels solid and well engineered. There is a lot of plastic, but it doesn't feel cheap or brittle, which is important given that it will be going through a lot of heating and cooling. The feet of the unit are actually metal bars instead of just plastic nubs or stick on rubber. It is this attention to detail that makes it feel like a luxury item. Getting started was really easy. I just plugged the unit in and turned it on. After selected the filament type from the menu all I had to do was let it run. The fans start circulating the heated air immediately and all the items in the display tell you the status. You can see the humidity decreasing on the display within minutes. The internal air circulation allows for very fast drying! I appreciate that the display is backlit for easy readability. My favorite feature of this unit is its ability to monitor the internal humidity and initiate drying when it rises above the selected threshold. The default is 50%, but it is can be set to your desired percentage. For humid environments this could be its best feature for sure! Of course you can adjust the temperature and humidity settings once you have selected from 1 of the 6 built in filament options. It is all very easily done from the front display and control panel. If you want you also enable an LED light to indicate when the unit is actively drying. You can also switch the unit to Fahrenheit or Celsius units for display. The unit is large, so plan for it to take up a fair amount of space. My hobby room is packed, so I had to get creative to make room for it. It is approximately 42cm L x 22cm D x 31cm H. I have seen a few other dryer on the market, but with the unit being able to actively dry 4 spools at a time, it is the best I have found.