The -P suffix is added to the part number to call out the “Open Frame Version.”
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VCE05US05 in the enclosed version, and the dimensions are 1.30" x 1.10" x 0.75” (33.02mm x 27.94mm x 19.05 mm) and weighs 0.053 lbs (24g)
VCE05US05-P is the Open Frame Version, and the dimensions are 1.20" x 1.00" x 0.705” (30.8mm x 25.4mm x 17.9 mm) and weight 0.03 lbs (14g)
Both versions will operate the same, and have the same electrical specifications and approval ratings.