Antoninianus - Probus radiate, draped; AEQVITAS AVG; Aequitas

(en) This coin is part of the 1st emission of Rome, therefore of the year 276 (Karl Pink, Der Aufbau der römischen Münzprägung in der Kaiserzeit VI/I, Wien, 1949). The coin was minted by the 3rd officina with the Greek letter 'Γ' sometimes as part of the exergue mark (-/-//XXIΓ) and sometimes as right field mark (-/Γ//XXI).

The original RIC text lists two variations, being two bust types (Bust type according to Pierre Bastiens grouping of bust types):
[1] radiate, draped, right (bust type A2), Numista N# 294696 (this coin);
[2] radiate, cuirassed, right (bust type B), Numista N# 293371;

For the first variant, RIC only mentions 'draped' and not also 'cuirassed'. Only 'draped' suggests bust type A. See for an example of bust type A from the Rome mint: probuscoins.fr #676 (RIC 240). The examples below suggest that 'cuirassed' was omitted by mistake because the non-B busts are all bust type A2: radiate, draped and cuirassed, right.

Other examples:
- probuscoins.fr #625 (bust B | -/Γ//XXI);
- probuscoins.fr #4385 (bust B | -/Γ//XXI);
- probuscoins.fr #4431 (bust B | -/Γ//XXI);
- probuscoins.fr #1173 (bust B | -/Γ//XXI);
- probuscoins.fr #194 (bust B | -/-//XXIΓ);
- probuscoins.fr #3646 (bust B | -/-//XXIΓ);
- probuscoins.fr #195 (bust A2 | -/Γ//XXI);
- probuscoins.fr #2337 (bust A2 | -/-//XXIΓ).

Mass varies (2.77–4.58 g) and the diameter varies (19,94–23 mm) according to
Online Coins of the Roman Empire (OCRE)