between adjoining wedge members 100 u2032 and 102 u2032 as taken along vertical center line 396 perpendicular to axis 384 ranges between 45 and 90 degrees those knowledgeable in the art will also realize that opposing wedges 100 u2032 and 102 u2032 can also be utilized to provide the desired flow restriction with substantially the same results as a single wedge as disclosed in the prior art in use each combined wedge 98 u2032 and cylindrical tube 381 must be pre calibrated in use referring to fig1 4 a housing 31 is selected for insertion in a fluid line to measure the fluid flow therethrough an inner member 80 comprising a specific 360 degree wedge 98 and tube 81 configuration is selected based upon the type of fluid to be measured and the flow rate to be measured thereby inner member 80 is telescopically inserted into first end 34 of housing 31 and aligned so that alignment pins 40 in circular recess 38 are received in alignment pin holes 88 of flange 86 as shown in fig4 engagement of pins 40 in holes 88 substantially centers first end 85 with respect to bore 42 as shown in fig2 upon full insertion chamfer 94 at second end 92 of inner member 80 is received by internal chamfer 39 of housing 31 the tapered surfaces of chamfers 39 and 94 interact such to center the second end 92 of inner cylindrical tube 81 within internal bore 82 of housing 31 flange 86 of inner member 80 is sealed against circular recess 38 and inner cylindrical tube 81 is centered along its length within internal bore 42 of housing 31 since the outer diameter of inner cylindrical tube 81 is smaller than bore 42 a space 110 as shown.