206 b with a segmented seat 1101 an obstruction 208 b is retained by the segmented seat 1101 and a pressure differential in the drilling fluid caused by the obstruction 208 b forces the obstruction 208 b and the reciprocating sleeve 206 b in direction 301 as the reciprocating sleeve 206 b moves in direction 301 b the segmented seat 1101 reaches a diametric relief 1103 and compliant segments 1102 allow the segmented seat 1101 to expand thereby allowing the obstruction 208 b to pass through the segmented seat 1101 and relieving the pressure differential drilling fluid may pass through slots 1151 formed between the compliant segments 1102 the total slot area is large enough to allow sufficient amounts of drilling fluid to pass through to maintain the drilling fluid functions downstream while allowing enough of a pressure build up to move the reciprocating sleeve 206 b forward in some embodiments pressure relief ports 1150 that relieve a portion of the pressure build up may be incorporated within an affected area the pressure relief ports 1150 are optimized to slow the pressure build up so sensors may have more time to sense the pressure increase fig1 a discloses an embodiment of a dart 1200 the dart 1200 comprises a hollow sleeve 1201 with a diametrically.