not shown and the upper end of a latch 2 the purposes of all which will be explained fully the latch 2 is constructed so that the lower end has fingers formed by longitudinal slots 27 in the lower portion of latch 2 these fingers are manufactured so as to be biased to the expanded and locked position there also exists a mandrel 1 connected to the top sub 6 and having a seal 9 to seal in apparatus b there is a through bore in apparatus a to allow the flow of well fluid the bore of apparatus a could also contain a mud saver valve to prevent fluid from falling to the rig floor or into the environment when apparatus a is disconnected from apparatus b a thread protector 3 of apparatus b contains surfaces to accept the latch 2 and seal 9 of apparatus a there is a through bore in thread protector 3 and tubular 8 to allow the flow of well fluid through the entire length of the tubular 8 referring now to fig2 a cross section of apparatus a and b as seen disconnected as in fig1 apparatus a has a central through bore 28 and apparatus b has a central through bore 29 in apparatus a top sub 6 is connected to mandrel 1 by threads 39 a seal 12 is located between top sub 6 and mandrel 1 seal 9 is located on mandrel 1 for sealing into apparatus b housing 4 is attached to the top sub 6 by threads 38 a piston 5 is located inside of housing 4 and operable by application of pressure through port 14 a piston chamber 15 better seen in fig2.