Need a custom plan?

If your puppy is outside the 12-24 lb starting range, or you are unsure which option to choose, fill out the form below. We’ll help you choose the safest and most cost-effective path as your puppy grows.

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Puppy Program FAQ

Are the growth-stage harnesses new?

Growth-stage harness kits may be gently used, fully inspected, maintained, and approved by Optimus Gear before being sent out. This helps us reduce waste and keep the Puppy Growth Program more affordable. Your final adult-size harness kit is yours to keep.

Do I keep every harness size?

No. The growth-stage kits are part of the program while your puppy is growing. Your final adult-size Optimus Gear harness kit is the one that is yours to keep.

What comes with each kit?

Each kit includes the Defender Harness, Upper Tether, Lower Tether, and Leash Converter. The program also includes fit help, setup guidance, video call support if needed, and ongoing sizing help as your puppy grows.

When do I switch sizes?

When your puppy is getting close to outgrowing their current fit, move them into the next size included in your program. If you are unsure, we can help check the fit with photos, videos, or a video call.

What if I choose the wrong growth path?

If you are unsure whether your puppy will finish in Medium, Large, or XL, contact us before ordering. We can help you choose based on your puppy’s breed, age, current weight, expected adult size, and photos.

What if my puppy starts under 12 lbs or over 24 lbs?


The standard options on this page are for puppies starting in Small, approximately 12–24 lbs. If your puppy is currently under 12 lbs or already over 24 lbs, fill out the custom plan form and we’ll help create the right program for your dog.

Is every size safe for car use?

Yes. Each stage is designed to give your puppy a properly fitted Optimus Gear in-car safety system for their size. The goal is to help your puppy start safer car habits early instead of waiting until they are fully grown.

What if my puppy chews part of the harness?

Puppies chew. Because we make and maintain our harness systems in-house, we can usually repair or replace straps as part of keeping the program moving. If there is major damage to the chest or back panel, we will review it with you and find the fairest solution.

When do I get the final harness?

Your final adult-size harness kit is provided when your dog reaches their adult size or is ready for their final program size. That final harness kit is yours to keep.

Do I need to know my puppy’s exact adult size before ordering?

No. You just need the best estimate. If you are unsure, we can help you choose the right growth path before you order.

What happens after I order?

After you order, we may follow up for details like your puppy’s breed, age, current weight, and photos so we can confirm the best starting fit before shipping.

Can I return the Puppy Growth Program?

Yes. You can return the Puppy Growth Program for a full money-back refund anytime before your dog receives their final adult-size harness kit.

We want you to have plenty of time to use the system, get help with the fit, and see how well it works before your puppy reaches their final size.

Once the final adult-size harness kit has been provided, it is yours to keep.