SolidTack MB are for flat surfaces
FlexTack are for curved and bent surfaces (2D curves, not 3D), without resorting to thick layers of glue.
“These self-adhesive mounting bases feature a high-performance acrylic adhesive which is specially designed to adhere strongly on high and low energy surfaces like metals, plastics, glass, painted, varnished or powder-coated objects,” claimed TTI.

The data sheet is not forthcoming on exactly how low that surface energy can be  – with they stick to polythese for example? See page 134 here (pdf page 115) for a little adhesive data.

FlexTack MMB is on page 135 (116).

HellermannTyton_SolidTack_Self-Adhesive-MountsSolidTack MB page 138 (pdf page 119) mounts are intended for electrical panels, telecoms cabinets and for fixing parts of wiring harnesses in railway carriages, aircraft or on vehicles where the use of screws or bolts is undesirable or impracticable.

Both products come in black or white and deliver initial adhesion, which increases with time and also offers weathering resistance.

Application is straightforward: peel off protection foil using the finger lift tab, and apply.

Mounts include four-way entry for cable ties.