Medallion Pools WA09042-4RRC 4' Reverse-Radius Corner for 42" Plain Panel Wall A090 Aluminum - This Reverse-Radius Corner is for use with a Medallion Pools 42" Plain Panel Wall. It is constructed of durable aluminum. Aluminum is an ideal choice for inground pools due to its rust resistance. Aluminum's flexibility is able to handle water movement while its strength can withstand cold temperatures.