The Heavy Duty Side Arms utilize a special vice clamp and are made with heavier materials.
In both cases, the Baby terminates in double 5/8" pins and the Junior in a single 1-1/8" Posi-V-Lock receiver.
CAUTION: When using a Side Arm, place a sandbag on the far leg with the same amount of weight as the light fixture. this will help prevent tipping of the stand.