The "green monster" usually refers to the USBR targets. I like using them for ammo testing and general practice. You can get those at Amazon.

Killough carries the ARA targets.

Amazon.com: USBR Official Targets (United States Bench Rest) 50 Yard, Green, 16" x 14" (50)

Amazon.com: USBR Official Targets (United States Bench Rest) 50 Yard, Green, 16" x 14" (50)

www.amazon.com

Unlimited Class Targets - PACK OF 100

The official Target of the American Rimfire Association, Inc. 25 Bulls and numerous sighters. these 22 targets are sold in packs of 100. Designed for .22lr benchrest competition at 50 yards. Can help with auto reset and is usable with 22 rimfire and 22lr ammo

www.killoughshootingsports.com

Factory Class Targets - PACK OF 100

The official Target of the American Rimfire Association New Factory Class, Inc. 25 Bulls and numerous sighters. Sold in packs of 100. Designed for .22lr bench rest factory class competition at 50 yards.

www.killoughshootingsports.com

 

Thank you Sophia
JK

 

The USBR target is challenging, I use it for practice.