Markings on the 52T one are "SG-X 52-B", markings on the 39T one are "SG-X 10S 39.8". 130BCD
Can throw in the chainring bolts if anyone's interested - they've got a torx head and were done up bastard tight.
Let's say £35 for the 52T, £15 for the 39T or £45 the pair. They've never been ridden.
Can post or deliver in person anywhere between central London and Enfield.