Pin Tumbler Padlocks
N

Click to Enlarge Image "NASA" - "BEST".  Body Type: Extruded. Body Material: Brass. Body Size: 1 1/2"Wx1 47/64"H. Shackle Material: Brass. Shackle Size: 5/16"Dx 1 7/8"H. Key Type: Single Sided 7 Pins. Mfg by: Best. (B1069).
"The Mike Pitman Collection"
9251
Click to Enlarge Image "N. T. CO". 1 1/2" wide. Brass case. Brass shackle. Made for: National Tube Co. Mfg by: Corbin Cabinet Lock Co.
"Courtesy Neil Pylant" 
2188
Click to Enlarge Image "N.T. Co SAFETY FIRST" - "BLOOM...". 2 11/16" high x 1 11/16" wide. Brass case. Brass shackle. Made for: National Tube Co.
"The Dave Parmalee Collection"
9125
Click to Enlarge Image "NTCo" - "YALE". Brass case. Brass shackle.  Made for: National Tube Co. Mfg by: Yale & Towne Mfg. Co.
"The Frank Kidd Collection"
6183