It's a standard 27.5" tube with auto 40mm length valve. STANDARD - doesn't mean ordinary: quality rubber compound combined with even wall thickness makes RFR tubes reliable and durable. RFR tubes were tested in laboratory!
For 27.5" tires
For tire width (ETRTO size in mm): from 47-584 to 54-584
Valve type: auto (Schrader / AV)
Valve length: 40 mm