The cordless impact driver is the tool you need for tough screws. Impact drivers have the power needed and they use both rotation and concussive blows to get the job done. Unfortunately, most impact drivers only know how to use brute force, they have no clutch. They can easily damage delicate material. For such jobs, you should use a combined cordless drills/driver or a cordless screwdriver. Despite all the power, an impact driver is easy and comfortable to operate, most of the power is transferred to the collet rather to your arm. Having a cordless drill and an impact driver makes you ready to take on a wide variety of tasks. A lot of vendors offer combo kits, including both a drill and an impact driver.
Here are the most popular impact drivers at the moment.
DEWALT DCF885B 20-Volt MAX Lithium-Ion 1/4-Inch Impact Driver
Customer Rating: 4.7 out of 5
Rating: 
The DEWALT DCF885B is an impact driver with incredible customer satisfaction. It is very powerful, compact and light-weight. It delivers 1400 inch-pounds, amazing amount of torque for such a compact impact driver. Note that you just get the impact driver, no battery or charger. If you don’t have DEWALT lithium-ion batteries and charger, it becomes pretty expensive but it is an excellent impact driver. On the other hand, if you already have batteries and charger, then you get very good value for your money. The DCF885B comes with a 3 year warranty. Here you can read more about the DEWALT DCF885B impact driver.
Porter-Cable PCCK640LB 20-volt 1/4-Inch Hex Lithium-Ion Impact Driver
Customer Rating: 4.7 out of 5
Rating:
If you want a really powerful impact driver, then the Porter-Cable PCCK640LB is the right impact driver for you. It provides an impressive 1,450 inch-pounds of torque. Despite being a powerful impact driver, the Porter-Cable PCCK640LB weighs only 3.2 pounds. It runs on lithium-ion, two batteries and one charger are included with the Porter-Cable PCCK640LB. If you are looking for a powerful impact driver and want excellent value for your money, then the Porter-Cable PCCK640LB is the right impact driver for you. Here you can read more about the Porter-Cable PCCK640LB Impact Driver.
DEWALT DCF815 12V 1/4-Inch Cordless Impact Driver
Customer Rating: 4.8 out of 5
Rating:
The DEWALT DCF815S2 12 Volt impact driver is impressive. It is an incredible combination of power, compact size and lightweight (just 2.2 pounds). To make things even better, it is priced at a very competitive level. You get excellent value for your money. Included in the kit are two lithium-ion battery packs, a bag, a charger, and a belt clip. Here you can read more about the DEWALT DCF815S2 impact driver.
It has become popular to buy a combo kit, consisting of a drill and an impact driver. It is a kit for the professional user. But if you are doing a lot of DIY tasks, it can be worth investing in a combo kit. Thanks to their popularity, a number of combo kits are available. Here are the most popular combo kits at the moment.
DEWALT DCK290L2 20-Volt MAX Li-Ion Hammer Drill and Impact Driver Combo Kit
Customer Rating: 4.7 out of 5
Rating:
Few combo kits include a hammer drill but the DEWALT DCK290L2 does, a really powerful cordless hammer drill, the DEWALT DCD985. It can be used as a hammer drill, as a standard drill or as a driver. The impact driver, DEWALT DCF885, is compact but very powerful. The DEWALT DCK290L2 is not a cheap combo kit but it gives you excellent value for your money. You get lightweight tools and excellent lithium-ion batteries. It has been one of the most popular combo kits for quite some time. Here you can read more about the DEWALT DCK290L2 Combo Kit.
Makita LXT211 18-Volt LXT Lithium-Ion Cordless 2-Piece Combo Kit
Customer Rating: 4.5 out of 5
Rating: 
A combo kit with a hammer drill let’s you drill in concrete and masonry as well. The Makita XT211 combo kit includes the LXPH01Z hammer drill, which can also be used as a driver. The impact driver is the Makita LXDT04Z, which delivers 1,420 inch-pound of torque. The kit includes two lithium-ion batteries (BL1830) and a 30-minute Rapid Optimum Charger. You also get a hard case and the kit is backed by a 3 year warranty. Makita XT211 combo kit gives you very good value for the money. Here you can learn more about the Makita XT211 combo kit.
Makita LCT209W 12V max Lithium-Ion Cordless 2-Piece Combo Kit
Customer Rating: 4.7 out of 5
Rating:
The Makita LCT209W combo kit contains two excellent tools, the Makita FD02W drill/driver and the DT01W impact driver. If you prefer compact and lightweight tools then this is the right combo kit for you. The 12V tools are not as powerful as 18V tools but they are capable of handling all normal tasks. The Makita LCT209W combo kit gives you excellent value for the money. Here you can read more about the Makita LCT209W Combo Kit.