What's mean of R in relays?

What's mean of R in relays?

In our automotive relays of MAH with 60A ,we have 3 brackets can choose for clients.

1 means this relay cover without bracket.

3 means this relay cover mental bracket.

4 means this relay cover plastic bracket, backrest plays a fixed role, which is more stable.

The relay with R can play a protective role when the impulse current is too large. For example, when the current is greater than or equal to 60A at the time of sudden braking, then this relay can protect the circuit very well.