The black 1.5 inch is used as adjusters with belts, collars, rifle slings, shoulder straps, bag straps, etc.
Dritz 1 Strap Adjusters, Slide, Black, 2 : Home & Kitchen
JWBIZ 8pcs Flat Metal Slide Buckle Belt Adjuster Sliders Tri Glide Strap Hardware Clasp (Gun Black, 1 1/4 Inch) : Arts, Crafts & Sewing
Double Loop Strap Metal Adjuster 1.75 Inch Black Plate 20134-13
Double Loop Strap Metal Adjuster 2 Inch Black Plate 20020-13
Strapworks 1/2 Inch Plastic Strap Adjuster Buckles - Black Slider Lock Buckle Great for Backpack and Utility Straps - 10 Pack (Model: PLH-SAJ-012-SAD-BLK-10P) : Arts, Crafts & Sewing
Ideal for use with bolt and spring snaps. Rope or straps slide easily through loop for a quick tie-down. Use 3/16 in. screws to fasten to wood material (not included).
Hillman Strap Loop 852713
Brass Double Loop Sliders, Triglides for Straps
Strapworks 1 1/2 inch Slider Buckles for Backpack Straps, Black, 25 Pack
CRAFTMEMORE 2 Inch Metal Slide Buckle Bag Belt Strap Keeper Slider Triglide Adjuster Purse Making Accessories 4 pcs SCSL (2 Inches Slider, Brushed Brass) : Arts, Crafts & Sewing
BIKICOCO Metal Slide Adjuster Buckle Tri-Glides with Movable Center Bar, for Straps, 2 x 0.8 Inch, Black, Pack of 10
Strapworks 1 1/2 inch Slider Buckles for Backpack Straps, Black, 25 Pack
1 Inch Plastic Strap Adjuster Double Adjust Black
Strapworks 1/2 Inch Plastic Strap Adjuster Buckles - Black Slider Lock Buckle Great for Backpack and Utility Straps - 10 Pack (Model: PLH-SAJ-012-SAD-BLK-10P) : Arts, Crafts & Sewing