Hair extensions Micro Bead and Hot Pre Bond! Micro bead : 16 inch full head £160.00( half head £110.00) 18 inch full head £180.00( half head £115.00) 20 inch full head £210.00( half head £125.00) For extra thick it is £50 +. Hot Pre Bond: 16 inch full head £160.00( half head £110.00) 18 inch full head £190.00( half head £120.00 20 inch full head £220.00( half head £130.00 For extra thick it is £60 *+.