SOLO is a waterproof tab that has with a carabiner (auto-locking for wide option) on one end and a D ring on the other end. The SOLO tab can be used flexibly as:

TRAINING TAB or PULL TAB
KEY HOLDER
CONNECTOR for other gears
HARNESS TO COLLAR SAFETY CLIP when adding another carabiner to D ring

Available in 2 widths:
NARROW ¾" or 2cm wide, 6" or 15cm long (all hardware included)
WIDE 1" or 2.5cm wide, 7" or 18cm long (all hardware included)

NARROW matches the width of AVA in S or OTTO in XS.
WIDE matches the width of AVA in M, L or OTTO in S, M, L.