Side by side.

Specification	SD-913 SD-913 Quote
Width	1.200"
Height	0.520"
Flange	0.185"
Material	Rubber
Type	Sponge
Durometer	2A4 (sponge grade)
Colour	Black
Mount	Push On
Bulb position	Side
Core	1.120in Wire
Industries	Heavy Trucks

Spec sheets live on each part's page.