New Swiftech H20-X20 Edge cooling kits

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jalyst: top is part of pump casing with specific shape cut out for pump's impeller. As stock one for DDC pumps is rather poorly designed (sharp 90deg angle in inlet reducing performance, instead of feeding water straight from top to center of impeller like custom tops do), using 3rd party tops usually noticeably increases pump performance, gives option to use any fittings of choice as have G1/4 threads, lessens noise and simply looks better . There are also several reservoirs with integrated pump tops (or in Edge kit case - radiators with integrated tops) to which you can mount rest parts of pump such as casing with engine & impeller, eg. such as by XSPC.
D5 stock top is better internal shape wise, so performance gains are minimal. You still get G1/4 threading & looks though.