Compare the recessed structure
Flat describes the external profile; inverted describes an inward-facing shape. Inspect the front and rear photographs separately, then compare the relevant opening, ring and connector measurements. A shared flat silhouette is not proof of identical internal geometry.
Choose accessories separately
The two examples below have different selectors and package information. Keep an optional insert distinct from the standard configuration, and do not use an accessory to compensate for an unsuitable fit. Follow the exact product instructions and keep removal access available.
Compare these configurations

The Inverted Penis Chastity Device combines a flat circular front with a flared, recessed opening on the reverse. It is a stainless-steel design with an upper keyed lock and an optional silicone catheter. This recessed structure gives it a different comparison role from a forward-projecting cage or a flat plate without an inverted opening.
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The Mini Inverted Flat Steel Chastity Cage has a shallow, perforated circular front and a keyed lock above the base ring. It gives shoppers a compact inverted-design comparison against deeper or forward-projecting cages. The listing specifies stainless steel in a silver colour, with a cage length of 16 mm and a cage diameter of 33 mm. Check the corresponding diagram before interpreting those figures as usable internal space.
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Review the measurement guide before choosing a configuration.
Inverted cages place the front profile differently from conventional designs. Compare the depth, ring attachment and exact package options of individual listings rather than assuming that all inverted models fit alike.
Compare flat chastity cage styles with micro cage designs. For a closer look at the trade-offs, read the inverted cage measurement guide.