Barrows Equipment

Does barrows equipment degrade by damage taken or the number of hits?

i.e.

can withstand up to 50,000 in damage.

or

can withstand up to 50,000 hits regardless of damage output done by the enemy.

The barrows equipment degrades purely on the time spent in combat, it doesn't matter how much damage you take or how much you are hit.

It used to say in the runescape knowledge database how long. I believe it was 15 hours of combat time to go from fully repaired to 0.

I'm not sure why they would remove that information from the knowledge db, but then they also removed times it takes for farming plots to grow.