Jr. – For small, short DSLR and mirrorless cameras on Helix Jr.
Standard – For midsize cameras like the Canon C100/C300
Heavy Duty – For large / long cameras like the SONY F55 and RED
Special differences to note:
The Helix Jr. base plate has a slot running sideways that simplifies balancing if optical centering is not required.
The heavy duty plate is angle adjustable via set screws (rods must be removed to see them). This helps compensate for any plate drooping due to front-heavy camera setups.