There are several different versions, including blocks for the nForce 680i, 975X and RD600. They cost between $38.50 and $42.95.
Features (note: some models have slightly different specs):
100% copper 110 material Acrylic and brass top options Threaded fitting ports are G 1/4 BSPP for use with any similar spec fittings. Complete Block with O-Ring Pressure Tested to 50psi High flow 1/4", 3/8", or 1/2" Chrome Plated Fittings Machine lapped and flat mirror polished Stainless steel hold down