EXCALIBUR
  HSA 12/100-Screwbolt-M
12 mm x 100 mm countersunk hexdrive bolt.
 upto 90mm embedment, 100mm overall length.
head is 28mm diameter with 10 mm In hexagon allen drive. 
yellow zinc passivated finish.
  drill a 12mm hole in stone /masonry/concrete etc and screw them in.
price per bolt. 
choose quantity required.