Front profile and internal space are different
An external flat shape does not state internal usable length or width. Look for the product’s own measurement diagram and distinguish cage dimensions from base-ring diameter. A Small or Standard label may refer to a different dimension on another product.
Compare the ring and lock as part of the shape
The front plate is only part of the assembled device. Ring geometry and the position of the lock can change the overall profile. Where Arc and Round choices are offered, compare them separately from the ring’s numerical size. An optional belt is another configuration choice, not an automatic inclusion.
Choose a design you can inspect and maintain
Openings, edges and removable components affect what you can see and access during inspection and cleaning. Follow the specific product instructions. No front pattern proves an appropriate wear duration, and a short body should not be selected to compensate for uncertain sizing.
Compare these configurations

Compare a circular flat front with your preferred ring geometry. This stainless steel model offers Arc or Round rings in 40, 45, 50 and 55 mm sizes. The package contains one selected ring, one cage and a lock with two keys, so the ring choice remains part of the purchase decision.
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The engraved owl front offers a decorative alternative within the flat category. Its listing specifies 304 stainless steel, a 35 mm cage diameter and four ring sizes. The belt is optional, making this a useful example of why shoppers should check the configuration as well as the main product photograph.
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Use the perforated front to compare coverage and opening pattern against a plain flat plate. This stainless steel design has five ring-size labels in its selector. Compare the corresponding size information rather than assuming Size 1 through Size 5 mean the same measurements as another model.
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For a different material within the flat profile, compare Flat Prison in ABS resin. A resin shell is not a stainless steel model. The Micro collection narrows the search by compact dimensions.