Abstract: A formation testing tool is described herein, including a formation probe assembly having an extendable sampling probe surrounded by a cylindrical sleeve. The sleeve is configured to engage a metal skirt having an elastomeric seal pad coupled thereto. The skirt and seal are configured to be field replaceable. The elastomeric pad has a non-planar outer surface which engages a borehole wall in preparation for formation testing. The seal pad may be donut-shaped, having an aperture through the middle of the seal pad. The seal pad and its surface may include numerous different embodiments, including having a curved profile. The seal pad may also include numerous different embodiments of means for coupling the seal pad to the metal skirt. The formation testing tool also includes formation probe assembly anti-rotation means, a deviated non-circular flowbore, and at least one closed hydraulic fluid chamber for balancing fluid pressures.