Straps, and I only use them on a handful of exercises - pullups, pulldowns, bb & t-bar rows, db/bb shrugs. I think anyone who can use an appreciable amount of weight on the above exercises aren't going to benefit fully if they don't use straps, hooks or something to help the grip. Reason why is you wanna fail due to muscle exhaustion, not grip exhaustion. I guarantee you're gonna get another rep or 2 doing bb rows/t-bars with 275+ lbs or shrugs with 400+ lbs. They help me the most with pull-ups - at 250lbs I can only do sets of 6-7 reps, and without straps it would be even less.