It is Alligator Clips/Crocodile Clamps, Rated current: 10A, Thickness of clip: 0.5mm or so. 

Mainly used in electric circuit, automotive, and battery-powered projects; will a best smart choice for electric engineer and electric DIY lover.

Specifications:

Thicken copper crocodile clip + thicken protective insulation sleeve

Rated current: 10A

Thickness of clip: 0.5mm or so

Opening range of clip: 10mm

Features:

PARAMETER --- rated current 10A; gator clip opening range 10mm; gator clip thickness 0.5mm.

APPLICATION --- electric circuit; automotive motors, fuel pumps and starters; battery-powered projects; HVAC system; test bench; fire alarm system troubleshooting.

FEATURE --- with thicken protective insulation sleeve, can cover clip entirely if needed.

QUANTITY --- 20 pcs.

NOTE:

1). Without wire;

2). The rivet can't be made of pure copper. Pure copper is too soft, which affects the service life and clamping force.

Package includes:

20 x Crocodile Alligator clip (10pcs Black + 10pcs Red)