I'm fairly certain this is what I picked up from McMaster-Carr for side feed o-rings a few years ago.
Line
Product
Ordered
Shipped
Balance
Price
Total
1
9263K124
Chemical-Resistant Viton Fluoroelastomer O-Ring, 2.5 mm Wide, 8 mm ID, Packs of 10
1
Pack
1
0
7.16
Per Pack
7.16
2
9263K776
Chemical-Resistant Viton Fluoroelastomer O-Ring, 3.5 mm Wide, 20 mm ID, Packs of 10
1
Pack
1
0
11.62
Per Pack
11.62