Boots of Haste

The Boots of Haste (not to be confused with the Dungeons and Dragons 5th Edition Boots of Speed) are an item that can be clicked together with a Bonus Action to cast the Haste spell on the wearer. They require attunement.

Properties
The Boots of Haste in Critical Role are a combination of the Boots of Speed from D&D 5e and the corresponding Boots of Speed from Pathfinder. Vax's boots follow the D&D rules for activation, but have the Pathfinder effect of casting Haste. Based on that, they would have the following properties:

''Requires Attunement While you wear these boots, you can use a Bonus Action and click the boots' heels together. If you do, you benefit from the effects of the Haste spell for the duration of this effect. If you click your heels together again, you end the effect. When the boots' property has been used for a total of 10 minutes, the magic ceases to function until you finish a Long Rest.''

Note that, unlike the actual Haste spell, the boots' effect does not require concentration and does not cause lethargy after use.

Campaign One: Vox Machina
Vax'ildan owns a pair of these boots that have caused a long-standing competition between him and his sister, Vex'ahlia. The feud began when Vax loaned the Boots of Haste to his sister in and she took a liking to them. Following that instance, she took every opportunity to steal the Boots for herself. Vax typically reclaims them within a short time, though sometimes only because his sister takes pity on him and gives them back.

Trivia

 * CritRoleStats has examined which of the twins actually gets the bigger benefit from these boots in Who Wore It Better: Boots of Haste.
 * Matthew Mercer has stated that the Boots of Haste are a holdover from the Pathfinder campaign, and were designed before he truly understood the "action economy" of D&D 5e. He has also made suggestions as to how they could be better balanced. Suggestions included adding a Concentration requirement, adding an effect consistent with the lethargy after Haste wears off, or only letting the effect last for 1d4+1 rounds.