Amazon.com: UHPPOTE Micro Small 125KHz RFID ID Proximity Induction Token Size 6(D) x26(L) mm/0.24x1.02in for Security Guard Patrol System(Pack of 10) : Electronics
Amazon.com: HECERE T5577 or UID chip RFID Black Ceramics Smart Finger rewrite Ring ID/IC Wear for Men or Women(UID IC-17MM) : Industrial & Scientific
Amazon.com: 125khz RFID Writable rewritable T5577 fob tag for RFID Writer (Pack of 10) (Black) : Electronics
Amazon.com: Proximity RFID Card 125KHZ EM4100 Read Only ID Smart Door Entry Access Control Plastic Card (pack of 10) -YARONGTECH : Electronics
Customised Version RFID 13.56mhz 1K UID Changeable & T5577 125khz Dual Chip Frequency IC/ID Key Tag Readable Writable Rewrite for Copy Clone Backu by XCRFID : Amazon.ca: Electronics
Amazon.com : Riversmerge RFID Rewritable 125KHz/13.56MHz ID/IC T5577/UID Changeable Black Ceramics Smart Finger Ring for Men or Women, with One RFID Reader Copier for Duplicate (Black 125khz 17mm) : Electronics
Amazon.com: 125khz RFID Card Copier Duplicator Handheld RFID Reader for Door Access Control +8pcs T5577 Key Fob Tags + 2pcs Regular EM4100 Wristband + 4pcs T5577 RFID Cards : Electronics
Amazon.com : Blue 100pcs 125Khz Proximity ID Card Chip TK EM 4100 RFID Tag Key Fob Keyfobs Keychain Ring Token for Access Control : Electronics
After testing a few 125 KHz RFID tags from Amazon, I found these to be the best. (More in comments below) : r/flipperzero
Amazon.com : LIBO Writable RFID Keychains 125KHz T5577 NFC Token Proximity ID Access Control Key Fob Tags Card Programable Blue Color (Pack of 100) : Electronics
Amazon.com: YARONGTECH USB RFID Reader 125KHZ EM4100 Desktop id Card Reader (8D) : Electronics
Amazon.com: YARONGTECH-10 PCS Writable 125kHz RFID Key Fob Proximity ID Card Token Tag Rewritable T5577 Universal : Electronics
Amazon.com: HFeng 125KHz T5577/EM4305 Writable RFID Keychains NFC Token Tags Proximity ID Access Control Key Fob Card Support Read and Write/Copy for Security Entry System Blue (10) : Electronics
Amazon.com : 125khz ID Card Reader Writer RFID Copier Duplicater for Access Control+5 PCS EM4305/T5557 Tags+ Copier Tool : Electronics
Amazon.com : JOJOCY 50 PCS ID 125KHz RFID Writable Rewritable T5577 Key Fob Tag for RFID Writer (Black) : Electronics
Amazon.com : 200pcs 125KHz Access Control Card Proximity EM4100 ID Smart Keycard for Door Electric Lock System : Electronics
Amazon.com : YARONGTECH Proximity EM4100 TK4100 125KHz RFID ID Card Tag Token Key Chain Keyfob Read Only Color Blue Pack of 100 : Electronics
Amazon.com: 125khz rfid key fob access em4100 tag read only (pack of 10) (black) : Industrial & Scientific
Amazon.com: YARONGTECH RFID Tag Proximity 125Khz Smart EM ID EM4100 Read Only Red Key Fobs Pack of 100 : Industrial & Scientific
Amazon.com: Dual Frequency RFID Key Fob 125Khz EM4100 and 13.56Mhz M1 chip (Pack of 10) (Blue) : Industrial & Scientific
BMES EM18 125Khz RFID Reader Module + 5 x 125Khz RFID Tags : Amazon.in: Industrial & Scientific
Amazon.com: 100pcs Ф25mm 125KHZ RFID T5557 Proximity Coin Fobs Tags Adhesive Sticker : Everything Else
Amazon.com : Handheld RFID ID Card Copier, 125kHz EM4305 RFID Proximity ID Card Reader/Writer/Duplicator, 10Pcs Writable 125kHz RFID Key Fob+10Pcs Contactless 125kHz RFID Proximity Smart Card : Electronics
