These vintage blades had original hard old rubber on them. I removed the rubber, sanded them smooth, and Urethaned the playing faces. The G1835 was one sided with black paint on back. The G1835 has a line on back side but it is rigid and not cracked. The rubber sheet came off the 1007 and it still feels soft and playable to me. It doesn't say PF4 but it is Double Happiness. These blade are ready for new rubber and to take down those big 2000 rated shake hand loopers in your club!