Is the stall ring hollow or solid?

Solid circle. Solid rings are more conducive to fixation and wear resistance. Because they are relatively large, they are usually used for activities such as stalls or summer barbecue markets. Hollow rings are generally used in heavy machinery, which can reduce the weight and be disassembled more easily. If stall needs to be reused, solid rings will be more durable than hollow rings because they can resist tension and torque and are easier to disassemble.