Equipped creature gets +1/+1 and has haste.
Equip( : Attach to target creature you control. Equip only as a sorcery.)
1/19/2018 If a creature enters the battlefield under your control and gains haste, but then loses it before attacking, it won’t be able to attack that turn. This means that you can’t use one Strider Harness to allow two new creatures to attack in the same turn.