Side by side.

Specification	BL-015 BL-015 Quote
Width	0.780"
Height	1.240"
Flange	0.125"
Material	Rubber
Type	Sponge
Durometer	2A3 (sponge grade)
Colour	Black
Mount	Push On
Bulb position	Side
Core	SD-487 Spring Steel
Industries	Emergency Vehicles

Spec sheets live on each part's page.