These were sent to be as a substitute for the Aquatop small sponge filters. I haven't had any issues with them being an inferior product.
I would recommend one of these per 10 gallons for fry and shrimp tanks.
Current Price: 5.99
Stock Level: 4
Store Name: TX Fish Factory LLC Store
Seller Country: United States
Shipping: Starts at $8.99 for up to 2 of these and may qualify for free shipping at checkout.