Based on this product's specifications, here are some alternatives and similar models
Surform shaver blade STANLEY 5-21-515 — pack of 3, 64×63 mm, compatible with model 21-115
Summary description:
Replacement Surform shaver blade from STANLEY (model 5-21-515). Pack contains 3 blades sized 64 mm × 63 mm designed for use with compatible Surform tool 21-115. Intended for shaping, smoothing and material removal on wood, plastics and soft materials. Useful for carpentry, model making and on-site adjustments where a Surform rasp is required.