how to determine piston ring size

{"cid":"91219924","title":"OM360 Piston Ring Set For Benz 115.00mm 3.5+3+5.5 Abrasion Resistance","imgUrl":"https:\/\/img.ismap.com\/nimg\/e2\/c0\/4edde0cee3a25494b463e8d802eb-200x200-1.jpg","attrs":{"Price":"Consult","Brand Name":"DEM","Model Number":"OM360","Minimum Order Quantity":"200 SETS","Delivery Time":"15days","Certification":"ISO 9001:2008 ISO\/TS16949","Place of Origin":"Zhejiang","Payment Terms":"T, T\/T, Western Union, MoneyGram","Supply Ability":"10000 SETS PER MONTH","Packaging Details":"CARTONS","Package":"Cartons","Car make":"Benz","Oem no.":"OM360","DIA.":"115.00mm","Thickness:":"115.00mm 3.5+3+5.5","No.cyl":"6","Type":"PISTON RING","Size":"Standard Size"}}

{"cid":"91213733","title":"6D125 6D125E-2 Diesel Engine Piston 6150-32-2110 For KOMATSU","imgUrl":"https:\/\/img.ismap.com\/nimg\/ae\/b2\/2ac792dafe640217c05778dfa36c-200x200-1.jpg","attrs":{"Price":"Looking forward to your inquiry","Brand Name":"HDPARTS","Model Number":"6D125 6D125E-2","Minimum Order Quantity":"1 set","Delivery Time":"2-5 work days","Place of Origin":"China","Payment Terms":"T\/T, Western Union, MoneyGram,HSBC","Supply Ability":"1000 Piece\/Pieces per Month","Packaging Details":"Plastic bag , Box , Carton","After Warran":"Online support","OEM Service":"Available","Packing":"Plastic bag , Box , Carton","Application":"Construction \/ Industry \/ Agriculture \/ Genset \/ Marine \/ Handling","Engine Type:":"Diesel","introduce":"High precision steel pipe materials","advantage":"Improve surface roughness"}}