I have 12 inches, after that I use 6 inches more often. For some reason the certified square was cheaper. 60's vs. 100's dollars. Has been certified.
Kapro - 353 Professional Ledge-It Try & Mitre Square - For Leveling And Measuring - Features Stainless Steel Blade, Retractable Ledge, And Etched Ruler Markings - 12 Inch
23 Review
Empire Level E250M: 12-Inch Heavy Duty Professional Combination Square with Etched π Stainless Steel Blade, Metric Graduations and True Blue Vial - Accurate Measurements Guaranteed
8 Review
Kapro 307-08-TMS Try And Mitre Layout And Marking Square With Stainless Steel Blade, 8-Inch Length
18 Review
π Johnson Level and Tool 400EM-S 12-Inch Heavy Duty Metal Combination Square for Professionals, with Inch/Metric Measurements, Silver - 1 Square
8 Review
Laser Level, 98Ft Green Self-Leveling Laser Line With Magnetic Base, With Adjustable Lightness Line Cross Laser Level For Picture Hanging - KAIWEETS T03
18 Review
21 Inch Heat Resistant Stove Gap Covers - Kitchen Counter Sealing Spills Protection (2 Pack, Semi-Clear)
21 Review
Precision Laser Level: Firecore 2X360 Self-Leveling Green Beam Tool With Pulse Mode And Rechargeable Battery For Accurate Alignment And Versatile Use
22 Review
ICEPURE 2PACK Replacement for GE MWFINT, 197D6321P006, WFC1201, GSH25JSDDSS, PSHS6PGZBESS, SGF-G9, RWF1060 Refrigerator Water Filter - Efficient Filtering Solution for Your Fridge
22 Review