I bought these two in the hope of upgrading some of my tool kit, but I've realised my limitations! I have two for sale: Norbar Professional 20-100 Nm, 1/2" drive - £60 posted Norbar TrueTorque TTi200 40-200 Nm, 1/2" drive - £70 posted. Both are brand new and unused, come complete with cases and calibration certificates from Norbar. Please don't confuse them with cheap torque wrenches, these are some of the best torque wrenches you can buy. I can post pictures if necessary.
I have a Norbar 10-50Nm 1/2" drive wrench - fantastic bit of kit. I have had it for 30 years and it is still good as new.
The quality of these torque wrenches is amazing - makes my Draper wrench look like a cheap Chinese knock off (which it probably is!).
Not sure how you can correct or calibrate but you can check at home using set weights (pounds) a set distance from the drive (feet) . There are you tube clips on how to check it's accuracy but it's not that expensive to have them calibrated anyway. Most engineering firms can check and adjust them.
Just bought 2 Norbar wrenches myself, tti 50 and tti250, Nice bits of kit for sure, Sold my 3 older wrenches (norbar/ britool and sykes) wernt worth getting calibrated because of the cost, These sold no probs at all on ebay, Worth calibrating if you have contacts. The wrenches that Halfords are selling are identical to the sykes ones I just sold( probably same manufacturer)
The Halfords wrenches are made in the UK by Norbar - the accredited test house certificate that comes with them has a UKAS Lab Number 0256 See the link: https://www.norbar.com/en-gb/Services/UKAS-Accredited-Laboratory