models/Inventory.js

```javascript
const mongoose = require('mongoose');

const inventorySchema = new mongoose.Schema({
    name: { type: String, required: true },
    sku: { type: String, required: true, unique: true },
    quantity: { type: Number, required: true },
    price: { type: Number, required: true },
    category: { type: String, required: true },
    threshold: { type: Number, required: true },
    lastUpdated: { type: Date, default: Date.now }
});

module.exports = mongoose.model('Inventory', inventorySchema);
```