Puma Electrify Nitro Ladies Running Shoes These Electrify Nitro Running Shoes from Puma have been engineered with NITRO FOAM in the heel which delivers advanced cushioning and response in a lightweight package. The shoes have a PMAGRIP outsole which combines durability and traction, while the mono mesh upper is lightweight and breathable so you can push yourself to get that new PB. The shoes benefit from a TPU heel insert which is reflective to help keep you safe when running in low light, whereas the Pro Foam technology offers durable cushioning and the forefoot rubber provides optimal bending stiffness.