[AtlUmpSteve]

Blocked ball, dead ball. If it interfered with a play on an advancing runner, out. If it had no bearing, where no play could have been made, dead ball immediately, return all runners to last base touched.

The only offensive equipment legally on the field is the batter's bat; anything else, including on deck batter's bat, must be off the field (in the hand), or is considered discarded. Warmup bats, bat attachments; anything.