When purchasing a penis extender, it's important to buy from a reputable and trustworthy source. Here are some tips for buying a penis extender:

1. Research the manufacturer: Before making a purchase, research the manufacturer of the penis extender to ensure that they are reputable and have a track record of producing safe and effective products.
2. Read customer reviews: Look for customer reviews and ratings of the penis extender to get a sense of the experiences other users have had with the product.
3. Check for certifications: Look for a penis extender that has been certified by regulatory agencies like the FDA, CE or Health Canada, as this can provide assurance that the device meets certain safety and efficacy standards.
4. Look for a warranty or guarantee: A warranty or guarantee can provide peace of mind and protect your investment in case the device doesn't work as intended.
5. Consider your budget: Penis extenders can range in price from less than $50 to several hundred dollars. Consider your budget and the value you place on the potential benefits when choosing a device.
6. Consult with a healthcare professional: If you have concerns about the size of your penis, or are considering using a penis extender to treat a medical condition like Peyronie's disease, it's important to consult with a healthcare professional to ensure that the device is appropriate for you and to get guidance on how to use it safely and effectively.