update: seller sent me a replacement screw down filter and a bonus gravity filter. For the excellent customer service I am adding a star to my original 2 star rating. The replacement still had an issue screwing down correctly. I think there may be a quality control issue with the threading. I fixed this by cutting off about 1/4 inches of the screw with a dremel so the filter would travel further down. After experimenting with the 2 types of filters I would say just go with the gravity filters. Its much easier to use and you dont have to worry about getting one with bad threads.

I might have received a defective filter. I bought a medium size and the filter doesnt screw down enough to pack the coffee correctly. I had to put in 3 tablespoons of coffee before the screw down part will even touch the top of the coffee. Besides the short thread of the filter, everything else seems well made. I think ill try a gravity type filter next since itll be easier to pack the coffee.

Okay phin filter. My issue with it is that the screw down insert does not screw down all the way inside. The shaft inside is fully threaded but the insert is threaded to go only about 1/3 the way down. So there is a lot of space between the insert and the bottom when you turn as far as it will go. The result is that I need to use about 2.5 - 3 tablespoons of coffee grounds to fill that space and enough compression of the grounds to achieve the recommended drip time of 4 minutes. Don't know if this is by design but i'm running through a can of coffee much quicker than I had anticipated.

Also, I wish there was a more textured nob when screwing the insert, its hard to grip sometimes.
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Edited 5/20/18

Seller reached out to me because of my initial 3 star review of the 8oz screw down type filter. Seller offered to send me the 8oz gravity type filter as a replacement. I accepted the offer and received the gravity type filter a few days later. Key differences between the screw down type and the gravity type:

-Screw down filter comes in 3 parts (brew chamber, screw down insert, and cap)
-Gravity filter comes in 4 parts (filter plate, brew chamber, gravity insert, and cap).
-It's much easier to compress the coffee grounds with the gravity type. With the screw down, you're at the mercy of how far the screw down insert goes.
-Cleaner brew with the gravity type as the coffee is passing through 2 layers (the brew chamber and the filter plate) versus the screw down type which only has 1 layer and consequently, some grounds finds its way through.
-Gravity type is easier to clean after brewing as you just pull out the insert and dump the grounds. Screw down type was tricky to unscrew after brewing cause of the coffee oils.
-Screw down type feels higher quality since it is all metal where as the gravity type has plastic nobs on either side for handling compared to the metal handle that the screw down type has.

I'm fortunate enough to live close by to an Asian market that stocks both Trung Nguyen and Cafe Du Monde coffees and have tried both. Both coffees work well in the gravity type filter. Just make sure to compress the coffee grounds a little before brewing. I haven't use the screw down type since receiving the gravity type.

5 star rating to the seller for standing behind the product and making things right.

Update 4/11/18
I was surprised to receive 2 additional filters (small and medium gravity filters) in the mail with an apology note + suggestions with different coffee grinds (they recommended I use Trung Nguyen instead of Cafe Du Monde). It was a nice gesture so I've bumped up the rating. After tinkering it with a bit, I think I got them to work correctly with Cafe Du Monde. I'll try out Trung Nguyen coffee next time.
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I'm not sure if I got a defective phin, but I bought the medium size to use with the Cafe Du Monde (the most typical grinds for Vietnamese coffee) and this thing drips waaaay too fast. I have literally tried every troubleshoot (add a little water to let the grinds expand, flatten the grinds evenly, add more grinds, screw it tighter, screw it looser, etc) and every time the water filters through in less than 30 seconds. Maybe the holes are larger as you buy bigger sizes? But I'm pretty upset how much coffee I've wasted trying to figure out how to use this properly. I might see how the small size is, or even see if the gravity filter will be better. But sucks how there are no returns.

1. use cafe du monde coffee, this is likely the closest flavor to what you think of as Vietnamese coffee in America
2. wet the coffee in the bottom with water 1/4th of the way up without the filter screwed down, this will allow the coffee to expand into a paste and greatly increase reduce water going through.
3. once coffee is wet and expanded, smooth with finger/spoon so coffee paste is level and there's no pockets water can go through, and screw down the top filter onto paste so it is compact and snug as can be. this will prevent the coffee from just pouring down through where ever air pockets are.
4. then fill the coffee container with water all the way up to the top, it should go through much slower and be much stronger, about 4 minutes

This coffee maker relies on a slow drip, about 4-5 minutes. I heat water up to boiling point. Then grind the beans at a medium grind , put base filter in pot, pour coffee over this filter and try to get the grinds level in the pot. A small tamper would work here. I am still working on this. Then screw the top filter on to stem of bottom filter. But not too tight or water may not get through. Try screwing down the top filter just enough to touch the grounds. Then pour in at least one cup of hot water. Back up: The pot needs to sit on top of coffee mug or glass, then pour water over it. Cover while dripping to save flavor. You can add milk before or after water is added, if you use it. This procedures is WELL worth the wait, because the flavor does not have the sharp bite that high pressure espresso machines can create. The result is strong but mellow! And that IS incredible! Ed