Side by side.

Specification	SD-124 SD-124 Quote
Width	1.140"
Height	0.550"
Flange	0.250"
Material	PVC
Second material	Rubber
Type	Sponge
Durometer	80 Shore A
Colour	Black
Mount	Push On
Bulb position	Side
Core	1in Stamped Steel

Spec sheets live on each part's page.