MAC Pro Longwear Concealer is a liquid concealer offering medium to full coverage. There's 9ml of product inside the glass bottle, which is a generous amount of concealer, because they usually contain around 6 ml product or less. It has a plastic pump dispenser which is pretty hard to control the amount of product you want to use, especially at the beginning, but with consistent use I've kind of figured out how to control it. As a consequence, you'll end up squeezing out more product than you need to use.
I find the coverage ranging between medium and buildable to full and the finish is natural matte. The consistency of the MAC Pro Longwear Concealer is lightweight, fluid and quite runny. I usually squeeze out a small amount (a little goes a long way) onto the back of my hand and then work the product onto the skin and blend either with fingers or a brush. Lately I've mainly been using it under my eyes for covering dark circles and brightening, because it's one of the lightest shades of concealers in my stash. It also covers redness and blemishes well, but with the latter I sometimes find that because of the liquid consistency I have to build up the product so much, I'd rather use something with a thicker formula that will deliver more coverage with initial application. I always set it with powder so it usually lasts on my skin all day without fading, doesn't get cakey with building up, but it can still crease on my under eyes if I don't set it quickly and therefor look slightly aging.
The shade NW15 has a balanced neutral undertone leaning slightly peachy on me, but it blends out seamlessly so it's not noticeable.
If you struggle with finding a perfect match for concealer, MAC has got you covered. The formula of their Pro Longwear Concealer isn't ideal (and the packaging isn't my favourite either), but it's still a really decent product. If I had to choose a favourite right now, it would either be the Collection Lasting Perfection Concealer in Fair or the Catrice Liquid Camouflage High Coverage Concealer in 005 Light Natural. MAC Pro Longwear Concealers are available here.