Boxcar - KF95 plates - speficially for their standard base on a flatbed cylinder-type proofing press www.boxcarpress.com/shop/kf95-letterpress-plate-scraps/
in this video we are using Boxcar's KF 95 scraps, which are generally up to 5" in any dimension www.boxcarpress.com/shop/kf95-letterpress-plate-scraps/