Here's a simple way for your partner to obey your "Spread 'Em" command. The cuffs are made of heavy-duty, quality nylon able to withstand your partner's movements, but also has soft neoprene on the inside to keep them comfortable. The spreader bar is firm, so they can't try to place their legs together. You secure the cuffs using Velcro.

Neoprene: Ankles are 16" apart and wrist are 9" apart.
Leather: Ankles are 22.5" apart and wrist are 23" apart.