second upper hollow open base hemispherical shaped member 34 that is displaced a distance from the first upper hollow open base hemispherical shaped member 22 and has a second upper member open base 36 the second upper hollow open base hemispherical shaped member 34 further has a second upper member front semi circular shaped throughbore 38 that opens into the second upper member open base 36 of the second upper hollow open base hemispherical shaped member 34 and has a second upper member front throughbore radius of curvature 40 that is equal to the first upper member front throughbore radius of curvature 28 of the first upper member front semi circular shaped throughbore 26 of the first upper hollow open base hemispherical shaped member 22 the second upper hollow open base hemispherical shaped member 34 further has a second upper member rear semi circular shaped throughbore 42 that is disposed in opposing alignment with the second upper member front semi circular shaped throughbore 38 of the second upper hollow open base hemispherical shaped member 34 the second upper member rear semi circular shaped throughbore 42 of the second upper hollow open base hemispherical shaped member 34 opens into the second upper member open base 36 of the second upper hollow open base hemispherical.