Cobra Chainstays are designed by Miyata to offer a generous amount of clearance for tires and dirt. They can be seen on second generation bonded and bolted (Koga) Miyata frames.
Cobra Chainstays allowed the use of tires up to 2.5". The stays were connected low to the bracket lug, with the intention to move them away from the chain and reduce chain slap. A bridge was left away, to prevent the accumulation of mud.