1.5mm X 6mm (NBR) Buna-N 70 Duro Metric O-Ring [N1.50X006] : The O-Ring Store LLC, We make getting O-Rings easy!
Metric Nitrile Rubber NBR O Ring Seals 1.5mm Cross Section 2mm-19mm Internal Dim | eBay
R-05 O-Ring (ID: 10 mm, CS: 1.5 mm, OD: 13 mm) by X1 Tools (10 to 120 O- Rings) | eBay
NBR O-ring 135 x 1.5mm (OD 138mm) 70 Shore A [10 Pieces] | Tameson.com
uxcell Fluorine Rubber O-Rings, 4mm OD 1mm ID 1.5mm Width FKM Seal Gasket for Machinery Plumbing, Green, Pack of 20: Amazon.com: Industrial & Scientific