EBayYou may have to adjust the fitment for a Fluval output. They are NOT consistent, unlike Loc-Line brand segmented lines. I personally hand fit 100% of these items to a Fluval Evo/Flex output line, but because they are inconsistent, there are instructions included as "how to" adjust them should yours be looser or tighter. Understand this before you buy as this is not a problem with the item, rather the manufacturers running changes and variances between suppliers of their components. If you are uncomfortable in adjusting them or can't communicate should you have issues or questions, please do not order. I pride myself in being as helpful as possible, but you must understand the potential before buying.  Each qty of 1 entered is for a PAIR (2) of small.25" Nozzles that fit the stock output of the Fluval Evo & Spec aquariums. The nozzles are not meant to ride near the surface of the water as that will most certainly cause suction of air and create bubbles, you need to have them reasonably below the surface to avoid this.  Are you looking to create a more natural environment in your reef, saltwater fish only or freshwater aquarium, then a Random Flow output nozzle is what will help you achieve those results. The nozzles create a turbulence that is not cyclical or patterned, which is more like natural water movement in the lake, rivers and oceans. These have been created to provide a snug fit that has been reinforced to avoid cracking. They are 3d printed with reef safe PETG filament and are made to order. In order to gain the maximum benefits, you will need stronger pump(s) to power these to their maximum potential. Photos in tank use are in my Fluval Evo 13.5G (black pair). Each and every nozzle is test fitted on a stock Fluval Evo output to make sure they fit correctly. With that said, Fluval has made running changes to their products and they may be slightly different from batch to batch. I include detailed instructions on how to make adjustments to tighten or loosen the fit if necessary, so please read them before installation to make sure you understand this.  If you have never purchased any sort of Loc-Line based products or anything that uses a Loc-Line ball type mount for an aquarium, you need to understand how the measurements are figured. If you order a 1/4" nozzle for example, the opening in the base will be much greater because "All Loc-Line hose systems are measured by the smallest diameter hole through the part." That is a direct quote from their website. I have included photos of the 3 sizes I offer so you can see the opening sizes and the sizes of the ball the nozzle will seat on. I have had people make bad reviews because they don't understand this and claim I mail the wrong sizes. If you have any questions at all, please ask prior to ordering to alleviate any potential problems such as these. Also, please understand that the nozzles have NO MOVING PARTS. The blades don't spin, there are no gears and the way they work is by venturi turbulence. The nozzles create varying flow patterns, not streams or constant straight output. If you have any questions, feel free to message me and I will help the best I can. I go above and beyond in most cases to make sure you know precisely what you will be receiving and how everything functions. The.25" Fitment is based on the Fluval flexible output fittings, these do NOT fit Loc-Line branded fittings. If you need the nozzle to fit the Loc-Line branded ball fitting, please see my other/future listing(s) for the correct fitment. Loc-Line brand flex fittings are slightly smaller and the nozzles will fit loose, if at all.  Understand, USPS has hiked up their rates again. Instead of reducing the "holiday rates" back to pre-holiday times, they instead jacked them higher. There's NOTHING I can do about that and I don't mark up for my packaging materials or time/gas to drive them to deliver. You know the costs before buying, if they're unacceptable don't make the purchase. I am a consumer just like you, I understand these factors before buying something and not going to ding someone for something they can't control. Benefits Include: More natural water movement Snug fitting, no loose sloppy nozzles Can be made to fit any system Eliminate bulky pumps from your display  No more dead flow spots in your reef  Printed In The USA (filament may be imported) Recommended Pump Output: 1/4" need at least 100gph/379lph and optimum 145gph/549lph (per nozzle) 1/2" need at least 150gph/568lph and optimum 400gph/1514lph (per nozzle) 3/4" need at least 200gph/758lph and optimum 475gph/1798lph (per nozzle)