Relays are indicated by the notation Rn.m (or sometime just Rm), where n is the shield index (0, 1, or 2), and m is the relay index, from the minimum to the maximum for that configuration. For example, on the ARDBOX 20 I/Os Relay HF+ shield, the relays range from R1 thru R8; the M-Duino 19+ shield relays range from R0.1 thru R0.8.

These products offer Relays.