combinations of straight and curved sections lower curved surface 870 includes a slight curvature like the upper curved surface 860 it may have a single radius of curvature or multiple further instead of a constant radius of curvature the lower curved surface may include a series of short straight sections that are each angled slightly from the preceding straight section still further the lower curved surface 860 may be combinations of straight and curved sections fig9 shows perspective view of sleeve retainer 900 sleeve retainer 900 is configured to secure nozzle 500 in bit 100 in the embodiment shown sleeve retainer 900 is threaded to match interior threads in bit 100 however one skilled in the art understands that other ways of securing sleeve retainer 900 are available sleeve retainer 900 also includes a top edge 910 shaped to assist in installation for example a tool can fit within the notches shown to tighten or loosen the sleeve retainer 900 fig1 shows a cut away side view of sleeve retainer 900 the sleeve retainer 900 has an inner area 920 that is sized and shaped to receive nozzle 500 in one embodiment inner area 920 is sized and shaped to receive the base 510 of curved nozzle 500 inner area 920 also includes shoulder 930 the shoulder 930 engages the step 530 between the base 510 and neck 520 of curved nozzle 500 in a preferred embodiment the shoulder 930 engages step 530 before the sleeve retainer 900 bottoms out in the nozzle socket 114 in this way the bottom of curved nozzle 500 is pressed firmly against bit 100 or alternatively against a gasket 1100 between the bottom of curved nozzle 500 and.