Hey man.
They are certainly good enough, but it would depend on what your strategy is and what your meta is like as to whether or not they are the best options.
I assume from your title that the part you are most after is the double mana rather than the creature buff. Is that correct?
It is worth noting that the effects on these cards is symmetrical, meaning it will also effect your opponents (in this case) red sources. If you find that you are the only one who is running red in any serious amount, then they are probably fine, but be wary that you could end up giving your opponents more advantage / benefit than you are getting yourself.
Also, there are a couple of other cards that do similar things just to put them on your radar:
Extraplanar Lens and
Mana Flare.
Gauntlet of Might is seriously expensive, so that may or may not have an impact on whether or not you wanted to include it.
Caged Sun would likely be a better option than
Gauntlet of Power. It's basically the same but it only effects your creatures and lands. It has a slightly higher cmc of 6 compared the the gauntlets 5, but personally I feel that that is a small price to pay for the effect being asymmetrical.
As well as that, if it's ramp you're after, generally mono colour decks fair well from just using mana rocks. There are a lot of efficient mana rocks that tap for multiple colourless mana such as
Sol Ring,
Worn Powerstone,
Thran Dynamo etc. Mono coloured decks can often take full advantage of these as they are less bothered by producing coloured mana from their ramp as their lands will generally cover all the coloured requirements for their spells.
Additionally, mono red has a half decent package of one off, explosive ramp options such as
desperate ritual,
mana geyser,
brass's bounty etc. Depending on what your strategy is, these could be of some use to you too.
Hope this helps!
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