I bought the Hario Next which came with the stainless filter and it’s been great. So great that When my brother got the TCA syphon as a gift, I knew he would find it a hassle to keep and maintain the cloth filter that came with it, or having to get the paper filter type and having to reorder more regularly. So I bought this for him. The other reviewer here has stated that s/he noticed some grinds had fallen through and was unsure if it’s because it’s not compatible with the Original TCA-# line of siphons. As far as I know Hario has stated that they are compatible. I also sometimes notice grinds come through but sometimes not so I think it may have something to do with ensuring centre placement and a good deal, rather than say grind size or anything like that (I usually use between a drip and espresso setting). I grind with the Breville Dose Control Pro burr grinder and the Smart Coffee Guide website has a chart of recommended grind settings for different coffee making methods. For syphon it is 16-44.
Another filter by Diguo seems to be quite popular but this one is by Hario themselves and retails for cheaper.