Sleds help the penguin leave the ramp higher and faster. There are two types of sled:
Sliding sleds: These require no effort and will automatically slide down the ramp at a high speed
Launching sleds: These are overall better than the sliding sleds although with these you must launch at the right time in order to get the highest jump
Plank: Really bad speed but better than without any sled. This is a sliding sled.
Plank Mark 2: Bad speed, but overall faster than the plank. This is a sliding sled.
Good Ol' Sled: This has pretty good speed and is a sliding sled.
Bobsled: This sliding sled is only second to the SuperSlide which can only be unlocked with the omega catalog.
Spring Box: This has a very slow speed but has a small take-off advantage since it is a launching sled.
E1 Bouncy: This has double the take-off and a bit faster than the spring box. This is a launching sled.
(ka)Boom Box: This launching sled is only second to the Omega Coil and has a pretty good take-off and has a slightly faster speed than the E1 Bouncy.
SuperSlide: This is the best sliding sled and has maximum speed to launch you off the ramp but it requires the omega catalog.
Omega Coil: This is overall the best sled but it is a launching sled (requiring effort) and has a low speed if you fail and you will also need the omega catalog.