Berkut had several modifications and missile types during its thirty years (1954..1984) of service.

6 system modifications: S-25, S-25M, S-25M2, S-25MA, S-25MAM, S-25MR
11 missile types: 205, 205A, 207, 207A, 215, 217M, 218, 5YA25, 5YA25M, 5Ya24, 44N6

The first S-25 version had only full lead guidance (S Standard method), as the first missile types had very low maneuverability (4g max), so the system could successfully engage only large and straight flying targets.

S-25M introduced the T (three point) guidance against jamming targets.

Pretty soon fast small, maneuverable targets were expected, so the S-25M2 transmit power was increased to 10MW (!!!), and the 217M type missile type could pull 14g (!!!).