In 1976 there was a hotly contentious debate between automakers. The up & coming automakers liked metrics. The old guard liked their standard. .45" bolt heads were what the old guard wanted, but the new crowd liked the sleeker, more streamlined 10mm. Arguments like "you get more per pack with 10mm" and "10mm wrenches are easier to use" and "10mm goes on faster and gets the job done better" beat out the argument that ".45" bolts let you use fewer bolts because they have a bigger hole, they're reliable and inches are what we've always used" and "Only a sissy has a problem controlling a .45 inch wrench" - and thus mechanics everywhere were made to embrace, love, and hate the 10mm. Side note, more 10mm wrenches, sockets, and 1/4 inch drives have been broken, lost, or thrown across the shop than all other metric or standard units combined in the last 40 years. in 2015 a fledgling movement called "10mm's matter" fizzled out as lobbiests from Harbor Freight, Snap On, Craftsman, Husky and Durabilt paid private security goons to pay a visit to local mechanic shops and warn them of the risks of protesting. Rumor has it that if you listen carefully to any 1980s or 90's shitbox ricer, you can hear the rattle of a lost 10mm wrench vibrating between the motor mount and engine block.