The Dometic Flush Ball Seal Kit is a replacement flush ball toilet seal for all Dometic 300 Series and 400 Series Gravity Flush Toilets. It includes seal and instructions only.• Mfr. No. 385311658• Outer Diameter: 4"• Inner Diameter: 2-3/4"The 385311658 Dometic Flush Ball Seal Kit is compatible with all Dometic 300 Series and 400 Series Gravity Flush Toilets: Model 400 EssentialModel 401 EssentialModel 410 CompleteModel 411 CompleteModel 420 PlatinumModel 421 PlatinumModel 300Model 301Model 310Model 311Model 320Model 321 4"" O.D. / 2-3/4"" I.D. hole | Dometic Flush Ball Seal Kit for 300 and 400 Series Toilets