A coupler (C) for securing an attachment (A) to an earth working machine , comprising: a coupler body that presents a receptacle (R1) comprising a mouth opening (M) via which a pin (P1) of an attachment (A) can pass to move through a passage (P) of the receptacle (R1) to a captive region (CR) of the receptacle (R1), a retainer moveably presented from and relative to the coupler body , the passage (P) of the receptacle (R1) being able to be at least partially occluded so as to prevent said pin (P1) from moving out of the captive region (CR) by said retainer of said coupler, wherein the retainer is biased to a passage occluded first position at which the retainer prevents said pin (P1) from moving out of the captive region (CR) and that can be moved to a second position relative the passage (P) to allow: (i) the ingress of said pin (P1) into the captive region (CR) by forcing said pin (P1) against the retainer to move the retainer against its bias towards said second position; and (ii) egress of said pin (P1) from the captive region (CR), by a driver of the coupler, wherein the driver is able to be moved relative the coupler body to be: (a) coupled with the retainer , to allow the retainer to be moved by the driver to its second position and (b) decoupled from the retainer , preventing the driver from moving the retainer's position, characterised in that the coupler (C) further comprises a trigger that is moveable relative the coupler body in a manner to be engaged and able to be moved by said pin (P1) as said pin (P1) moves through the passage (P) in a manner so that the trigger can, when so moved by said pin (P1), cause the driver to decouple from the retainer , preventing the driver from moving the retainer's position. a coupler body that presents a receptacle (R1) comprising a mouth opening (M) via which a pin (P1) of an attachment (A) can pass to move through a passage (P) of the receptacle (R1) to a captive region (CR) of the receptacle (R1), a retainer moveably presented from and relative to the coupler body , the passage (P) of the receptacle (R1) being able to be at least partially occluded so as to prevent said pin (P1) from moving out of the captive region (CR) by said retainer of said coupler, wherein the retainer is biased to a passage occluded first position at which the retainer prevents said pin (P1) from moving out of the captive region (CR) and that can be moved to a second position relative the passage (P) to allow: (i) the ingress of said pin (P1) into the captive region (CR) by forcing said pin (P1) against the retainer to move the retainer against its bias towards said second position; and (ii) egress of said pin (P1) from the captive region (CR), by a driver of the coupler, (i) the ingress of said pin (P1) into the captive region (CR) by forcing said pin (P1) against the retainer to move the retainer against its bias towards said second position; and (ii) egress of said pin (P1) from the captive region (CR), by a driver of the coupler, (a) coupled with the retainer , to allow the retainer to be moved by the driver to its second position and (b) decoupled from the retainer , preventing the driver from moving the retainer's position, <EOS>