The upper only configuration of our chain guide. This is for frames that only have mounts for an upper chain guide or those who want the most minimal chain retention option. Weighing only 28g for a 32T or 31g for a 30T, you will be hard pressed to find something lighter that can hold the chain in place as well as this. Our patent pending guide geometry renders dropping a chain off the top of the ring impossible even if you try. Others may claim to deliver this level of chain retention, but we've been down that path and dropped chains still.