I've always used spirit levels and very rarely my iPhone to level things, but with both you don't have a way to 'set' the spirit level. This allows you to set the zero plane anywhere you like, making finding rafter angles 10 times easier than digging up a combination angle and measuring.
Laser level HiLDA 4D/16 set 4
44 Review
π Kapro 905-41-24 24-Inch Level Tool - Premium Bubble Level with Shockproof End Caps, Superior Accuracy & Visibility, Optivision Red and Plumb Site Dual View Vial, Condor Spirit Level
10 Review
π SKIL 24-Inch Digital Level - LV941901
8 Review
DigiPas DWL80PRO: Compact Digital Level & Angle Gauge - Accurate Protractor, Bevel Gauge, and Angle Finder, 0.05Β° Sensitivity, 4 inch Pocket Size
11 Review
Kapro 307-08-TMS Try And Mitre Layout And Marking Square With Stainless Steel Blade, 8-Inch Length
18 Review
π² Johnson RAS-1B Johnny Square: Professional Aluminum Rafter Square, 7'', Silver - Top Quality with 1 Square
8 Review
Triangle Group TR918 225/45 R18 95V summer
61 Review
π CAMWAY 6 Inch Digital Caliper with LCD Display, Electronic Vernier Caliper, 150mm Stainless Steel Feeler Gauge, Plastic Digital Caliper Set for Zero Setting Inside/Outside Diameter, Depth, and Step Measurement Tool
3 Review