Lap straps are probably the most versatile seat belt/restraint. They can be made to suit your requirements with a virtually unlimited range of lengths for the lap belt and a vast array of buckle types and anchor plates. They can be made to suit most applications.

Standard static lap strap (left)
Fitted with flat anchor plates and fixed length webbing buckle.

Static lap strap with 90°anchor plates (right)
Fitted with adjustor built into webbing buckle allowing both ends to be adjusted to suit your application.

These are just two of the lap belts available.