Will this fit under a lowered car or truck?

At 40" wide, it's designed to nestle between tire tracks on most vehicles. For heavily lowered builds, test-fit under your specific vehicle before committing to regular use — ground clearance varies by suspension setup.

Do the casters lock in place?

Locking mechanism not specified — roll the creeper into position and verify stability before sliding under the vehicle. If locking is critical to your workflow, check that feature before checkout.

Can I use this creeper outdoors or just in the garage?

Hard panel construction handles both concrete and asphalt. For wet conditions, let it dry before flipping between creeper and seat mode to avoid moisture pooling on the work surface.