I beg to differ, having used both types. I have also used cheapo chinese retracts that were identical to the Supras, right down to the green anodized color. I have used the browninsh ones from Great Planes, also.
I have nothing against great planes...I can only say from FIRST HAND EXPERIENCE of actually flying them that these identical-appearing retracts are NOT the same. The material they use is different. If you fly off of grass, fugeddaboutit.
I have broken one of the original EZ Supra ones, too, but that was an out-and-out crash, not their fault. The other left side supra retract is still in the airplane. The right one has gone though BOTH of the Great Planes ones and one of the Chinese ones. They broke under very, very minor stress, all in the same place, too.
I will be installing all metal springairs instead, but that's my personal taste.
EZ and Supra ARE the same retract, same brand. EZ and GP are not. GP is the same as the unbranded chinese ones.