Antoninianus - Probus imperial mantle, left; SECVRIT PERP; Securitas

Reverse

Securitas, draped, standing left, legs crossed, leaning on column, raising right hand to head.

Script: Latin

Lettering:
SECVRIT PERP
-/I//VIXXI

Translation:
Securitas Perpetua.
To perpetual security.

Comment

About RIC 525
The original RIC text lists two variations, being two bust types (bust type according to Pierre Bastiens grouping of bust types). Also one variant is known:
[1] Radiate, cuirassed, right (bust type B), ;
[2] Radiate, wearing imperial mantle, left, holding sceptre surmounted by eagle in right hand (bust type H2), this coin;
[3] [var] Radiate, wearing imperial mantle, right, holding sceptre surmounted by eagle in right hand (bust type H4, see probuscoins.fr #1249);

This coin was minted by the 6th officina (exergue mark VIXXI) of Ticinum. RIC only mentions the right field mark 'I', but the 'I' is also commonly depicted on the left.

According to Pink (Karl Pink, Der Aufbau der römischen Münzprägung in der Kaiserzeit VI/I, Wien, 1949), the 6th officina used the reverse title 'SECVRIT PERP', combined with obverse legend 'IMP C PROBVS AVG' (in Pink's article: legend nr. 7), the exergue mark VIXXI and the field mark I, during the 9th emission, which was in the year 281. Also commonly included under RIC 525 is the variation on this version with the H2 bust, with the field mark 'I' and '✶', which is, according to Pink, part of the 10th emission (282).

This coin is part of the EQVITI series of Ticinum, which is, according to Pink, part of the 8th, 9th and 10th emission. In the EQVITI series, the 6th officina represents the letter I (EQVITI) as field mark. See on these coded series: Gert Boersema, The Translation of the Codewords AEQVITI, IOBI and HPKOY, Forumancientcoins.com, 2007.

See for other examples of this coin:
- Probuscoins.fr #309 (right field mark 'I');
- Probuscoins.fr #1960 (left field mark 'I');
- Probuscoins.fr #1255 (field mark '✶/I').

Interesting fact