I used fertility2family brand, bought them off eBay in a pack I think it was about $20 for 60 OPKs and 20 hpts. I think it was my first or second month of using them that I fell pregnant so the OPKs work well. The hpts I didn't get a positive with for a couple of days after i got my one with FRER at 10dpo started getting faints with the f2f ones at 12dpo. Good luck!