Pinhead Bike Saddle Anti-Theft Lock for 31.6mm & 27.2mm Seatposts 564-P12 | eBay
Pinhead Seatpost/Saddle Lock QR - 28.6/27.2.
Today I installed pinhead locks to my RadExpand 5 seatpost and front wheel. Those were the only parts compatible, but feels justified for the cost of replacements! : r/RadPowerBikes