One Size Secure the Blur Makeup Magnet Primer can be found in various retail outlets, both physical and online. Here are a few options:

1. Sephora: One Size is available at most Sephora stores and on their website. You can use the store locator feature on Sephora's website to find the nearest location.

2. Ulta Beauty: Although One Size is primarily sold at Sephora, some products might be available at Ulta Beauty. Check their website or visit a local store to confirm.

3. One Size Official Website: You can purchase the primer directly from the One Size official website.

4. Amazon: Some One Size products may be available on Amazon. However, ensure you're buying from a trusted seller to avoid counterfeit products.

Remember to check the product's availability at your local stores or their websites before visiting, as stock can vary.