I need to take the rear calipers of my car. My 14mm socket is worn and starting to round the corners off the heads so i’m going to buy a new one.
What should I be looking for to deal with old bolt heads?

non worn and good quality.

i bought halfords pro kit and it took off bolts i previously though were beyond removal without an irwin socket

halfords pro kit

for a shop with such a reputation for selling sh*t, halfords socket sets are surprisingly good
also, a thurough dousing of wd40 should help

Try a new, quality, six sided socket in the right size.

Get surface drive sockets – work well on worn bolt heads

Seconded —- single hex 14mm .

When you say the car is old are you sure the bolt heads/nuts metric or imperial?

+ ^^^^^^ 6 sided/hex/surface drive,proper size & fit

Have you managed to get some release agent of some sort into the thread? Squirt/spray and leave for 15/20mins. Descent industrial one not WD40
Use a punch and give the head of the bolt a good sharp clout.
Try tightening before loosening

I have one of those tools above = useless for most things.Still reort to the tied and tested hammer & chisel 😛

‘Old’ is car 10 years old so metric I think. plenty of WD already as thats all I’ve got at the mo.
Main problem is Mrs Sb has disappeared with the other car so i can’t even go and get new socket!