How to Choose Between Models

3 Options to consider.

Side Color? (Red or Green) - The Color of the sides is personal preference, the best selling color is Forest Green. Models with Red sides are popular as gifts, there is no difference in performance between the two colors.
Wire Finish? "Copper-Gold Iridescent" or "Satin Black" - The color of the wire is mostly personal preference, both finishes have similar weather resistance properties. Satin Black is a solid coating and it has a UV Topcoat. The black tends to blend-in more with the forest green sides and it has a more subtle look. The Black Satin Finish is best selling finish and most popular finish. The Copper-Gold Iridescent finished wire is also weather resistant and an accent to the green or red sides. The Copper-Gold wire can change between copper and gold depending on viewing angle and sunlight. Copper-Gold tends to have a custom-crafted appearance (compared to a solid color) because each part turns out a little different during the finishing process. We have named both colors "Goldfinch Copper-Gold Iridescent" and "Black-Capped Chickadee Black" < click links to see colors.
Seed Hopper? (Polycarbonate Plastic or Steel) - The Seed Hopper choice is the biggest difference in the models - read about the hopper differences below.

Note:

All models are guaranteed squirrel proof.

Example #1

Forest Green Sides, Gold Wire, Steel Seed Hopper

Rf2 Cardinal squirrel proof bird feeder by RollerFeeder.

Steel Seed Hopper versus Polycarbonate Hopper?

Steel Seed Hopper

2 Full length feeding trays & stainless mesh sides.

Steel Seed Hopper is more heavy duty than plastic for tough animal problems like raccoons or large aggressive squirrels.
Steel Seed Hopper has stainless steel mesh feeding sides and full length trays (both sides). Birds can pick seeds from the sides of the hopper or seed trays. There is also more exposed seed to pick seeds from the sides or trays.
Steel Seed Hopper has tighter seed trays to prevent seed spillage during aggressive squirrel attempts.
Steel Seed Hopper accommodates black oil sunflower seed or sunflower in the shell/sunflower hearts/safflower mix/small peanut parts. This seed mix is considered one of the best bird seed mixes.
Mesh sided hopper can also be used as a squirrel proof peanut-parts feeder.
Steel Hopper is available in 2 quart (standard) or 2.5 quart extra-capacity size with 25% more capacity. Approx. 2-3/4 lbs of seed using sunflower hearts & extra capacity hopper.

Polycarbonate Plastic Hopper

2 Full length trays with steel edges.

Plastic hopper accommodates all seed types.
Plastic Hopper has full length seed trays, both sides - the seed trays are a little larger than the steel hopper.
Plastic Hopper is medium-duty versus more heavy duty steel above.
Plastic Hopper has steel tray edges to prevent squirrel damage, Steel is built-in.
Plastic Hopper is clear for a little better view of the bird seed but both hopper types do well since the seed is exposed in the steel mesh sides, shown in above feeder.
Plastic hopper is available in 2 quart capacity hopper size. Approx. 2-1/4 lbs of seed using sunflower hearts.