Park Tool Single Speed Spanner - SS-15C Updated for 2011 Now 37% lighter the SS-15 includes a 15mm socket for axle nuts a 15mm open end wrench for pedals a stiff and durable tire lever and a bottle opener Just the right size and length (17cm/7) to take along or to wrench in the garage, the SS-15 is destined to be a single speeders favorite.